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-------------------------------------------------------------------------------
- T H E /proc F I L E S Y S T E M
-------------------------------------------------------------------------------
-/proc/sys Terrehon Bowden <terrehon@pacbell.net> October 7 1999
- Bodo Bauer <bb@ricochet.net>
-
-2.4.x update Jorge Nerin <comandante@zaralinux.com> November 14 2000
-move /proc/sys Shen Feng <shen@cn.fujitsu.com> April 1 2009
-------------------------------------------------------------------------------
-Version 1.3 Kernel version 2.2.12
- Kernel version 2.4.0-test11-pre4
-------------------------------------------------------------------------------
-fixes/update part 1.1 Stefani Seibold <stefani@seibold.net> June 9 2009
-
-Table of Contents
------------------
-
- 0 Preface
- 0.1 Introduction/Credits
- 0.2 Legal Stuff
-
- 1 Collecting System Information
- 1.1 Process-Specific Subdirectories
- 1.2 Kernel data
- 1.3 IDE devices in /proc/ide
- 1.4 Networking info in /proc/net
- 1.5 SCSI info
- 1.6 Parallel port info in /proc/parport
- 1.7 TTY info in /proc/tty
- 1.8 Miscellaneous kernel statistics in /proc/stat
- 1.9 Ext4 file system parameters
-
- 2 Modifying System Parameters
-
- 3 Per-Process Parameters
- 3.1 /proc/<pid>/oom_adj & /proc/<pid>/oom_score_adj - Adjust the oom-killer
- score
- 3.2 /proc/<pid>/oom_score - Display current oom-killer score
- 3.3 /proc/<pid>/io - Display the IO accounting fields
- 3.4 /proc/<pid>/coredump_filter - Core dump filtering settings
- 3.5 /proc/<pid>/mountinfo - Information about mounts
- 3.6 /proc/<pid>/comm & /proc/<pid>/task/<tid>/comm
- 3.7 /proc/<pid>/task/<tid>/children - Information about task children
-
- 4 Configuring procfs
- 4.1 Mount options
-
-------------------------------------------------------------------------------
-Preface
-------------------------------------------------------------------------------
-
-0.1 Introduction/Credits
-------------------------
-
-This documentation is part of a soon (or so we hope) to be released book on
-the SuSE Linux distribution. As there is no complete documentation for the
-/proc file system and we've used many freely available sources to write these
-chapters, it seems only fair to give the work back to the Linux community.
-This work is based on the 2.2.* kernel version and the upcoming 2.4.*. I'm
-afraid it's still far from complete, but we hope it will be useful. As far as
-we know, it is the first 'all-in-one' document about the /proc file system. It
-is focused on the Intel x86 hardware, so if you are looking for PPC, ARM,
-SPARC, AXP, etc., features, you probably won't find what you are looking for.
-It also only covers IPv4 networking, not IPv6 nor other protocols - sorry. But
-additions and patches are welcome and will be added to this document if you
-mail them to Bodo.
-
-We'd like to thank Alan Cox, Rik van Riel, and Alexey Kuznetsov and a lot of
-other people for help compiling this documentation. We'd also like to extend a
-special thank you to Andi Kleen for documentation, which we relied on heavily
-to create this document, as well as the additional information he provided.
-Thanks to everybody else who contributed source or docs to the Linux kernel
-and helped create a great piece of software... :)
-
-If you have any comments, corrections or additions, please don't hesitate to
-contact Bodo Bauer at bb@ricochet.net. We'll be happy to add them to this
-document.
-
-The latest version of this document is available online at
-http://tldp.org/LDP/Linux-Filesystem-Hierarchy/html/proc.html
-
-If the above direction does not works for you, you could try the kernel
-mailing list at linux-kernel@vger.kernel.org and/or try to reach me at
-comandante@zaralinux.com.
-
-0.2 Legal Stuff
----------------
-
-We don't guarantee the correctness of this document, and if you come to us
-complaining about how you screwed up your system because of incorrect
-documentation, we won't feel responsible...
-
-------------------------------------------------------------------------------
-CHAPTER 1: COLLECTING SYSTEM INFORMATION
-------------------------------------------------------------------------------
-
-------------------------------------------------------------------------------
-In This Chapter
-------------------------------------------------------------------------------
-* Investigating the properties of the pseudo file system /proc and its
- ability to provide information on the running Linux system
-* Examining /proc's structure
-* Uncovering various information about the kernel and the processes running
- on the system
-------------------------------------------------------------------------------
-
-
-The proc file system acts as an interface to internal data structures in the
-kernel. It can be used to obtain information about the system and to change
-certain kernel parameters at runtime (sysctl).
-
-First, we'll take a look at the read-only parts of /proc. In Chapter 2, we
-show you how you can use /proc/sys to change settings.
-
-1.1 Process-Specific Subdirectories
------------------------------------
-
-The directory /proc contains (among other things) one subdirectory for each
-process running on the system, which is named after the process ID (PID).
-
-The link self points to the process reading the file system. Each process
-subdirectory has the entries listed in Table 1-1.
-
-
-Table 1-1: Process specific entries in /proc
-..............................................................................
- File Content
- clear_refs Clears page referenced bits shown in smaps output
- cmdline Command line arguments
- cpu Current and last cpu in which it was executed (2.4)(smp)
- cwd Link to the current working directory
- environ Values of environment variables
- exe Link to the executable of this process
- fd Directory, which contains all file descriptors
- maps Memory maps to executables and library files (2.4)
- mem Memory held by this process
- root Link to the root directory of this process
- stat Process status
- statm Process memory status information
- status Process status in human readable form
- wchan If CONFIG_KALLSYMS is set, a pre-decoded wchan
- pagemap Page table
- stack Report full stack trace, enable via CONFIG_STACKTRACE
- smaps a extension based on maps, showing the memory consumption of
- each mapping
-..............................................................................
-
-For example, to get the status information of a process, all you have to do is
-read the file /proc/PID/status:
-
- >cat /proc/self/status
- Name: cat
- State: R (running)
- Tgid: 5452
- Pid: 5452
- PPid: 743
- TracerPid: 0 (2.4)
- Uid: 501 501 501 501
- Gid: 100 100 100 100
- FDSize: 256
- Groups: 100 14 16
- VmPeak: 5004 kB
- VmSize: 5004 kB
- VmLck: 0 kB
- VmHWM: 476 kB
- VmRSS: 476 kB
- VmData: 156 kB
- VmStk: 88 kB
- VmExe: 68 kB
- VmLib: 1412 kB
- VmPTE: 20 kb
- VmSwap: 0 kB
- Threads: 1
- SigQ: 0/28578
- SigPnd: 0000000000000000
- ShdPnd: 0000000000000000
- SigBlk: 0000000000000000
- SigIgn: 0000000000000000
- SigCgt: 0000000000000000
- CapInh: 00000000fffffeff
- CapPrm: 0000000000000000
- CapEff: 0000000000000000
- CapBnd: ffffffffffffffff
- voluntary_ctxt_switches: 0
- nonvoluntary_ctxt_switches: 1
-
-This shows you nearly the same information you would get if you viewed it with
-the ps command. In fact, ps uses the proc file system to obtain its
-information. But you get a more detailed view of the process by reading the
-file /proc/PID/status. It fields are described in table 1-2.
-
-The statm file contains more detailed information about the process
-memory usage. Its seven fields are explained in Table 1-3. The stat file
-contains details information about the process itself. Its fields are
-explained in Table 1-4.
-
-(for SMP CONFIG users)
-For making accounting scalable, RSS related information are handled in
-asynchronous manner and the vaule may not be very precise. To see a precise
-snapshot of a moment, you can see /proc/<pid>/smaps file and scan page table.
-It's slow but very precise.
-
-Table 1-2: Contents of the status files (as of 2.6.30-rc7)
-..............................................................................
- Field Content
- Name filename of the executable
- State state (R is running, S is sleeping, D is sleeping
- in an uninterruptible wait, Z is zombie,
- T is traced or stopped)
- Tgid thread group ID
- Pid process id
- PPid process id of the parent process
- TracerPid PID of process tracing this process (0 if not)
- Uid Real, effective, saved set, and file system UIDs
- Gid Real, effective, saved set, and file system GIDs
- FDSize number of file descriptor slots currently allocated
- Groups supplementary group list
- VmPeak peak virtual memory size
- VmSize total program size
- VmLck locked memory size
- VmHWM peak resident set size ("high water mark")
- VmRSS size of memory portions
- VmData size of data, stack, and text segments
- VmStk size of data, stack, and text segments
- VmExe size of text segment
- VmLib size of shared library code
- VmPTE size of page table entries
- VmSwap size of swap usage (the number of referred swapents)
- Threads number of threads
- SigQ number of signals queued/max. number for queue
- SigPnd bitmap of pending signals for the thread
- ShdPnd bitmap of shared pending signals for the process
- SigBlk bitmap of blocked signals
- SigIgn bitmap of ignored signals
- SigCgt bitmap of catched signals
- CapInh bitmap of inheritable capabilities
- CapPrm bitmap of permitted capabilities
- CapEff bitmap of effective capabilities
- CapBnd bitmap of capabilities bounding set
- Cpus_allowed mask of CPUs on which this process may run
- Cpus_allowed_list Same as previous, but in "list format"
- Mems_allowed mask of memory nodes allowed to this process
- Mems_allowed_list Same as previous, but in "list format"
- voluntary_ctxt_switches number of voluntary context switches
- nonvoluntary_ctxt_switches number of non voluntary context switches
-..............................................................................
-
-Table 1-3: Contents of the statm files (as of 2.6.8-rc3)
-..............................................................................
- Field Content
- size total program size (pages) (same as VmSize in status)
- resident size of memory portions (pages) (same as VmRSS in status)
- shared number of pages that are shared (i.e. backed by a file)
- trs number of pages that are 'code' (not including libs; broken,
- includes data segment)
- lrs number of pages of library (always 0 on 2.6)
- drs number of pages of data/stack (including libs; broken,
- includes library text)
- dt number of dirty pages (always 0 on 2.6)
-..............................................................................
-
-
-Table 1-4: Contents of the stat files (as of 2.6.30-rc7)
-..............................................................................
- Field Content
- pid process id
- tcomm filename of the executable
- state state (R is running, S is sleeping, D is sleeping in an
- uninterruptible wait, Z is zombie, T is traced or stopped)
- ppid process id of the parent process
- pgrp pgrp of the process
- sid session id
- tty_nr tty the process uses
- tty_pgrp pgrp of the tty
- flags task flags
- min_flt number of minor faults
- cmin_flt number of minor faults with child's
- maj_flt number of major faults
- cmaj_flt number of major faults with child's
- utime user mode jiffies
- stime kernel mode jiffies
- cutime user mode jiffies with child's
- cstime kernel mode jiffies with child's
- priority priority level
- nice nice level
- num_threads number of threads
- it_real_value (obsolete, always 0)
- start_time time the process started after system boot
- vsize virtual memory size
- rss resident set memory size
- rsslim current limit in bytes on the rss
- start_code address above which program text can run
- end_code address below which program text can run
- start_stack address of the start of the main process stack
- esp current value of ESP
- eip current value of EIP
- pending bitmap of pending signals
- blocked bitmap of blocked signals
- sigign bitmap of ignored signals
- sigcatch bitmap of catched signals
- wchan address where process went to sleep
- 0 (place holder)
- 0 (place holder)
- exit_signal signal to send to parent thread on exit
- task_cpu which CPU the task is scheduled on
- rt_priority realtime priority
- policy scheduling policy (man sched_setscheduler)
- blkio_ticks time spent waiting for block IO
- gtime guest time of the task in jiffies
- cgtime guest time of the task children in jiffies
- start_data address above which program data+bss is placed
- end_data address below which program data+bss is placed
- start_brk address above which program heap can be expanded with brk()
- arg_start address above which program command line is placed
- arg_end address below which program command line is placed
- env_start address above which program environment is placed
- env_end address below which program environment is placed
- exit_code the thread's exit_code in the form reported by the waitpid system call
-..............................................................................
-
-The /proc/PID/maps file containing the currently mapped memory regions and
-their access permissions.
-
-The format is:
-
-address perms offset dev inode pathname
-
-08048000-08049000 r-xp 00000000 03:00 8312 /opt/test
-08049000-0804a000 rw-p 00001000 03:00 8312 /opt/test
-0804a000-0806b000 rw-p 00000000 00:00 0 [heap]
-a7cb1000-a7cb2000 ---p 00000000 00:00 0
-a7cb2000-a7eb2000 rw-p 00000000 00:00 0
-a7eb2000-a7eb3000 ---p 00000000 00:00 0
-a7eb3000-a7ed5000 rw-p 00000000 00:00 0 [stack:1001]
-a7ed5000-a8008000 r-xp 00000000 03:00 4222 /lib/libc.so.6
-a8008000-a800a000 r--p 00133000 03:00 4222 /lib/libc.so.6
-a800a000-a800b000 rw-p 00135000 03:00 4222 /lib/libc.so.6
-a800b000-a800e000 rw-p 00000000 00:00 0
-a800e000-a8022000 r-xp 00000000 03:00 14462 /lib/libpthread.so.0
-a8022000-a8023000 r--p 00013000 03:00 14462 /lib/libpthread.so.0
-a8023000-a8024000 rw-p 00014000 03:00 14462 /lib/libpthread.so.0
-a8024000-a8027000 rw-p 00000000 00:00 0
-a8027000-a8043000 r-xp 00000000 03:00 8317 /lib/ld-linux.so.2
-a8043000-a8044000 r--p 0001b000 03:00 8317 /lib/ld-linux.so.2
-a8044000-a8045000 rw-p 0001c000 03:00 8317 /lib/ld-linux.so.2
-aff35000-aff4a000 rw-p 00000000 00:00 0 [stack]
-ffffe000-fffff000 r-xp 00000000 00:00 0 [vdso]
-
-where "address" is the address space in the process that it occupies, "perms"
-is a set of permissions:
-
- r = read
- w = write
- x = execute
- s = shared
- p = private (copy on write)
-
-"offset" is the offset into the mapping, "dev" is the device (major:minor), and
-"inode" is the inode on that device. 0 indicates that no inode is associated
-with the memory region, as the case would be with BSS (uninitialized data).
-The "pathname" shows the name associated file for this mapping. If the mapping
-is not associated with a file:
-
- [heap] = the heap of the program
- [stack] = the stack of the main process
- [stack:1001] = the stack of the thread with tid 1001
- [vdso] = the "virtual dynamic shared object",
- the kernel system call handler
-
- or if empty, the mapping is anonymous.
-
-The /proc/PID/task/TID/maps is a view of the virtual memory from the viewpoint
-of the individual tasks of a process. In this file you will see a mapping marked
-as [stack] if that task sees it as a stack. This is a key difference from the
-content of /proc/PID/maps, where you will see all mappings that are being used
-as stack by all of those tasks. Hence, for the example above, the task-level
-map, i.e. /proc/PID/task/TID/maps for thread 1001 will look like this:
-
-08048000-08049000 r-xp 00000000 03:00 8312 /opt/test
-08049000-0804a000 rw-p 00001000 03:00 8312 /opt/test
-0804a000-0806b000 rw-p 00000000 00:00 0 [heap]
-a7cb1000-a7cb2000 ---p 00000000 00:00 0
-a7cb2000-a7eb2000 rw-p 00000000 00:00 0
-a7eb2000-a7eb3000 ---p 00000000 00:00 0
-a7eb3000-a7ed5000 rw-p 00000000 00:00 0 [stack]
-a7ed5000-a8008000 r-xp 00000000 03:00 4222 /lib/libc.so.6
-a8008000-a800a000 r--p 00133000 03:00 4222 /lib/libc.so.6
-a800a000-a800b000 rw-p 00135000 03:00 4222 /lib/libc.so.6
-a800b000-a800e000 rw-p 00000000 00:00 0
-a800e000-a8022000 r-xp 00000000 03:00 14462 /lib/libpthread.so.0
-a8022000-a8023000 r--p 00013000 03:00 14462 /lib/libpthread.so.0
-a8023000-a8024000 rw-p 00014000 03:00 14462 /lib/libpthread.so.0
-a8024000-a8027000 rw-p 00000000 00:00 0
-a8027000-a8043000 r-xp 00000000 03:00 8317 /lib/ld-linux.so.2
-a8043000-a8044000 r--p 0001b000 03:00 8317 /lib/ld-linux.so.2
-a8044000-a8045000 rw-p 0001c000 03:00 8317 /lib/ld-linux.so.2
-aff35000-aff4a000 rw-p 00000000 00:00 0
-ffffe000-fffff000 r-xp 00000000 00:00 0 [vdso]
-
-The /proc/PID/smaps is an extension based on maps, showing the memory
-consumption for each of the process's mappings. For each of mappings there
-is a series of lines such as the following:
-
-08048000-080bc000 r-xp 00000000 03:02 13130 /bin/bash
-Size: 1084 kB
-Rss: 892 kB
-Pss: 374 kB
-Shared_Clean: 892 kB
-Shared_Dirty: 0 kB
-Private_Clean: 0 kB
-Private_Dirty: 0 kB
-Referenced: 892 kB
-Anonymous: 0 kB
-Swap: 0 kB
-KernelPageSize: 4 kB
-MMUPageSize: 4 kB
-Locked: 374 kB
-
-The first of these lines shows the same information as is displayed for the
-mapping in /proc/PID/maps. The remaining lines show the size of the mapping
-(size), the amount of the mapping that is currently resident in RAM (RSS), the
-process' proportional share of this mapping (PSS), the number of clean and
-dirty private pages in the mapping. Note that even a page which is part of a
-MAP_SHARED mapping, but has only a single pte mapped, i.e. is currently used
-by only one process, is accounted as private and not as shared. "Referenced"
-indicates the amount of memory currently marked as referenced or accessed.
-"Anonymous" shows the amount of memory that does not belong to any file. Even
-a mapping associated with a file may contain anonymous pages: when MAP_PRIVATE
-and a page is modified, the file page is replaced by a private anonymous copy.
-"Swap" shows how much would-be-anonymous memory is also used, but out on
-swap.
-
-This file is only present if the CONFIG_MMU kernel configuration option is
-enabled.
-
-The /proc/PID/clear_refs is used to reset the PG_Referenced and ACCESSED/YOUNG
-bits on both physical and virtual pages associated with a process.
-To clear the bits for all the pages associated with the process
- > echo 1 > /proc/PID/clear_refs
-
-To clear the bits for the anonymous pages associated with the process
- > echo 2 > /proc/PID/clear_refs
-
-To clear the bits for the file mapped pages associated with the process
- > echo 3 > /proc/PID/clear_refs
-Any other value written to /proc/PID/clear_refs will have no effect.
-
-The /proc/pid/pagemap gives the PFN, which can be used to find the pageflags
-using /proc/kpageflags and number of times a page is mapped using
-/proc/kpagecount. For detailed explanation, see Documentation/vm/pagemap.txt.
-
-1.2 Kernel data
----------------
-
-Similar to the process entries, the kernel data files give information about
-the running kernel. The files used to obtain this information are contained in
-/proc and are listed in Table 1-5. Not all of these will be present in your
-system. It depends on the kernel configuration and the loaded modules, which
-files are there, and which are missing.
-
-Table 1-5: Kernel info in /proc
-..............................................................................
- File Content
- apm Advanced power management info
- buddyinfo Kernel memory allocator information (see text) (2.5)
- bus Directory containing bus specific information
- cmdline Kernel command line
- cpuinfo Info about the CPU
- devices Available devices (block and character)
- dma Used DMS channels
- filesystems Supported filesystems
- driver Various drivers grouped here, currently rtc (2.4)
- execdomains Execdomains, related to security (2.4)
- fb Frame Buffer devices (2.4)
- fs File system parameters, currently nfs/exports (2.4)
- ide Directory containing info about the IDE subsystem
- interrupts Interrupt usage
- iomem Memory map (2.4)
- ioports I/O port usage
- irq Masks for irq to cpu affinity (2.4)(smp?)
- isapnp ISA PnP (Plug&Play) Info (2.4)
- kcore Kernel core image (can be ELF or A.OUT(deprecated in 2.4))
- kmsg Kernel messages
- ksyms Kernel symbol table
- loadavg Load average of last 1, 5 & 15 minutes
- locks Kernel locks
- meminfo Memory info
- misc Miscellaneous
- modules List of loaded modules
- mounts Mounted filesystems
- net Networking info (see text)
- pagetypeinfo Additional page allocator information (see text) (2.5)
- partitions Table of partitions known to the system
- pci Deprecated info of PCI bus (new way -> /proc/bus/pci/,
- decoupled by lspci (2.4)
- rtc Real time clock
- scsi SCSI info (see text)
- slabinfo Slab pool info
- softirqs softirq usage
- stat Overall statistics
- swaps Swap space utilization
- sys See chapter 2
- sysvipc Info of SysVIPC Resources (msg, sem, shm) (2.4)
- tty Info of tty drivers
- uptime System uptime
- version Kernel version
- video bttv info of video resources (2.4)
- vmallocinfo Show vmalloced areas
-..............................................................................
-
-You can, for example, check which interrupts are currently in use and what
-they are used for by looking in the file /proc/interrupts:
-
- > cat /proc/interrupts
- CPU0
- 0: 8728810 XT-PIC timer
- 1: 895 XT-PIC keyboard
- 2: 0 XT-PIC cascade
- 3: 531695 XT-PIC aha152x
- 4: 2014133 XT-PIC serial
- 5: 44401 XT-PIC pcnet_cs
- 8: 2 XT-PIC rtc
- 11: 8 XT-PIC i82365
- 12: 182918 XT-PIC PS/2 Mouse
- 13: 1 XT-PIC fpu
- 14: 1232265 XT-PIC ide0
- 15: 7 XT-PIC ide1
- NMI: 0
-
-In 2.4.* a couple of lines where added to this file LOC & ERR (this time is the
-output of a SMP machine):
-
- > cat /proc/interrupts
-
- CPU0 CPU1
- 0: 1243498 1214548 IO-APIC-edge timer
- 1: 8949 8958 IO-APIC-edge keyboard
- 2: 0 0 XT-PIC cascade
- 5: 11286 10161 IO-APIC-edge soundblaster
- 8: 1 0 IO-APIC-edge rtc
- 9: 27422 27407 IO-APIC-edge 3c503
- 12: 113645 113873 IO-APIC-edge PS/2 Mouse
- 13: 0 0 XT-PIC fpu
- 14: 22491 24012 IO-APIC-edge ide0
- 15: 2183 2415 IO-APIC-edge ide1
- 17: 30564 30414 IO-APIC-level eth0
- 18: 177 164 IO-APIC-level bttv
- NMI: 2457961 2457959
- LOC: 2457882 2457881
- ERR: 2155
-
-NMI is incremented in this case because every timer interrupt generates a NMI
-(Non Maskable Interrupt) which is used by the NMI Watchdog to detect lockups.
-
-LOC is the local interrupt counter of the internal APIC of every CPU.
-
-ERR is incremented in the case of errors in the IO-APIC bus (the bus that
-connects the CPUs in a SMP system. This means that an error has been detected,
-the IO-APIC automatically retry the transmission, so it should not be a big
-problem, but you should read the SMP-FAQ.
-
-In 2.6.2* /proc/interrupts was expanded again. This time the goal was for
-/proc/interrupts to display every IRQ vector in use by the system, not
-just those considered 'most important'. The new vectors are:
-
- THR -- interrupt raised when a machine check threshold counter
- (typically counting ECC corrected errors of memory or cache) exceeds
- a configurable threshold. Only available on some systems.
-
- TRM -- a thermal event interrupt occurs when a temperature threshold
- has been exceeded for the CPU. This interrupt may also be generated
- when the temperature drops back to normal.
-
- SPU -- a spurious interrupt is some interrupt that was raised then lowered
- by some IO device before it could be fully processed by the APIC. Hence
- the APIC sees the interrupt but does not know what device it came from.
- For this case the APIC will generate the interrupt with a IRQ vector
- of 0xff. This might also be generated by chipset bugs.
-
- RES, CAL, TLB -- rescheduling, call and TLB flush interrupts are
- sent from one CPU to another per the needs of the OS. Typically,
- their statistics are used by kernel developers and interested users to
- determine the occurrence of interrupts of the given type.
-
-The above IRQ vectors are displayed only when relevant. For example,
-the threshold vector does not exist on x86_64 platforms. Others are
-suppressed when the system is a uniprocessor. As of this writing, only
-i386 and x86_64 platforms support the new IRQ vector displays.
-
-Of some interest is the introduction of the /proc/irq directory to 2.4.
-It could be used to set IRQ to CPU affinity, this means that you can "hook" an
-IRQ to only one CPU, or to exclude a CPU of handling IRQs. The contents of the
-irq subdir is one subdir for each IRQ, and two files; default_smp_affinity and
-prof_cpu_mask.
-
-For example
- > ls /proc/irq/
- 0 10 12 14 16 18 2 4 6 8 prof_cpu_mask
- 1 11 13 15 17 19 3 5 7 9 default_smp_affinity
- > ls /proc/irq/0/
- smp_affinity
-
-smp_affinity is a bitmask, in which you can specify which CPUs can handle the
-IRQ, you can set it by doing:
-
- > echo 1 > /proc/irq/10/smp_affinity
-
-This means that only the first CPU will handle the IRQ, but you can also echo
-5 which means that only the first and fourth CPU can handle the IRQ.
-
-The contents of each smp_affinity file is the same by default:
-
- > cat /proc/irq/0/smp_affinity
- ffffffff
-
-There is an alternate interface, smp_affinity_list which allows specifying
-a cpu range instead of a bitmask:
-
- > cat /proc/irq/0/smp_affinity_list
- 1024-1031
-
-The default_smp_affinity mask applies to all non-active IRQs, which are the
-IRQs which have not yet been allocated/activated, and hence which lack a
-/proc/irq/[0-9]* directory.
-
-The node file on an SMP system shows the node to which the device using the IRQ
-reports itself as being attached. This hardware locality information does not
-include information about any possible driver locality preference.
-
-prof_cpu_mask specifies which CPUs are to be profiled by the system wide
-profiler. Default value is ffffffff (all cpus if there are only 32 of them).
-
-The way IRQs are routed is handled by the IO-APIC, and it's Round Robin
-between all the CPUs which are allowed to handle it. As usual the kernel has
-more info than you and does a better job than you, so the defaults are the
-best choice for almost everyone. [Note this applies only to those IO-APIC's
-that support "Round Robin" interrupt distribution.]
-
-There are three more important subdirectories in /proc: net, scsi, and sys.
-The general rule is that the contents, or even the existence of these
-directories, depend on your kernel configuration. If SCSI is not enabled, the
-directory scsi may not exist. The same is true with the net, which is there
-only when networking support is present in the running kernel.
-
-The slabinfo file gives information about memory usage at the slab level.
-Linux uses slab pools for memory management above page level in version 2.2.
-Commonly used objects have their own slab pool (such as network buffers,
-directory cache, and so on).
-
-..............................................................................
-
-> cat /proc/buddyinfo
-
-Node 0, zone DMA 0 4 5 4 4 3 ...
-Node 0, zone Normal 1 0 0 1 101 8 ...
-Node 0, zone HighMem 2 0 0 1 1 0 ...
-
-External fragmentation is a problem under some workloads, and buddyinfo is a
-useful tool for helping diagnose these problems. Buddyinfo will give you a
-clue as to how big an area you can safely allocate, or why a previous
-allocation failed.
-
-Each column represents the number of pages of a certain order which are
-available. In this case, there are 0 chunks of 2^0*PAGE_SIZE available in
-ZONE_DMA, 4 chunks of 2^1*PAGE_SIZE in ZONE_DMA, 101 chunks of 2^4*PAGE_SIZE
-available in ZONE_NORMAL, etc...
-
-More information relevant to external fragmentation can be found in
-pagetypeinfo.
-
-> cat /proc/pagetypeinfo
-Page block order: 9
-Pages per block: 512
-
-Free pages count per migrate type at order 0 1 2 3 4 5 6 7 8 9 10
-Node 0, zone DMA, type Unmovable 0 0 0 1 1 1 1 1 1 1 0
-Node 0, zone DMA, type Reclaimable 0 0 0 0 0 0 0 0 0 0 0
-Node 0, zone DMA, type Movable 1 1 2 1 2 1 1 0 1 0 2
-Node 0, zone DMA, type Reserve 0 0 0 0 0 0 0 0 0 1 0
-Node 0, zone DMA, type Isolate 0 0 0 0 0 0 0 0 0 0 0
-Node 0, zone DMA32, type Unmovable 103 54 77 1 1 1 11 8 7 1 9
-Node 0, zone DMA32, type Reclaimable 0 0 2 1 0 0 0 0 1 0 0
-Node 0, zone DMA32, type Movable 169 152 113 91 77 54 39 13 6 1 452
-Node 0, zone DMA32, type Reserve 1 2 2 2 2 0 1 1 1 1 0
-Node 0, zone DMA32, type Isolate 0 0 0 0 0 0 0 0 0 0 0
-
-Number of blocks type Unmovable Reclaimable Movable Reserve Isolate
-Node 0, zone DMA 2 0 5 1 0
-Node 0, zone DMA32 41 6 967 2 0
-
-Fragmentation avoidance in the kernel works by grouping pages of different
-migrate types into the same contiguous regions of memory called page blocks.
-A page block is typically the size of the default hugepage size e.g. 2MB on
-X86-64. By keeping pages grouped based on their ability to move, the kernel
-can reclaim pages within a page block to satisfy a high-order allocation.
-
-The pagetypinfo begins with information on the size of a page block. It
-then gives the same type of information as buddyinfo except broken down
-by migrate-type and finishes with details on how many page blocks of each
-type exist.
-
-If min_free_kbytes has been tuned correctly (recommendations made by hugeadm
-from libhugetlbfs http://sourceforge.net/projects/libhugetlbfs/), one can
-make an estimate of the likely number of huge pages that can be allocated
-at a given point in time. All the "Movable" blocks should be allocatable
-unless memory has been mlock()'d. Some of the Reclaimable blocks should
-also be allocatable although a lot of filesystem metadata may have to be
-reclaimed to achieve this.
-
-..............................................................................
-
-meminfo:
-
-Provides information about distribution and utilization of memory. This
-varies by architecture and compile options. The following is from a
-16GB PIII, which has highmem enabled. You may not have all of these fields.
-
-> cat /proc/meminfo
-
-The "Locked" indicates whether the mapping is locked in memory or not.
-
-
-MemTotal: 16344972 kB
-MemFree: 13634064 kB
-Buffers: 3656 kB
-Cached: 1195708 kB
-SwapCached: 0 kB
-Active: 891636 kB
-Inactive: 1077224 kB
-HighTotal: 15597528 kB
-HighFree: 13629632 kB
-LowTotal: 747444 kB
-LowFree: 4432 kB
-SwapTotal: 0 kB
-SwapFree: 0 kB
-Dirty: 968 kB
-Writeback: 0 kB
-AnonPages: 861800 kB
-Mapped: 280372 kB
-Slab: 284364 kB
-SReclaimable: 159856 kB
-SUnreclaim: 124508 kB
-PageTables: 24448 kB
-NFS_Unstable: 0 kB
-Bounce: 0 kB
-WritebackTmp: 0 kB
-CommitLimit: 7669796 kB
-Committed_AS: 100056 kB
-VmallocTotal: 112216 kB
-VmallocUsed: 428 kB
-VmallocChunk: 111088 kB
-AnonHugePages: 49152 kB
-
- MemTotal: Total usable ram (i.e. physical ram minus a few reserved
- bits and the kernel binary code)
- MemFree: The sum of LowFree+HighFree
- Buffers: Relatively temporary storage for raw disk blocks
- shouldn't get tremendously large (20MB or so)
- Cached: in-memory cache for files read from the disk (the
- pagecache). Doesn't include SwapCached
- SwapCached: Memory that once was swapped out, is swapped back in but
- still also is in the swapfile (if memory is needed it
- doesn't need to be swapped out AGAIN because it is already
- in the swapfile. This saves I/O)
- Active: Memory that has been used more recently and usually not
- reclaimed unless absolutely necessary.
- Inactive: Memory which has been less recently used. It is more
- eligible to be reclaimed for other purposes
- HighTotal:
- HighFree: Highmem is all memory above ~860MB of physical memory
- Highmem areas are for use by userspace programs, or
- for the pagecache. The kernel must use tricks to access
- this memory, making it slower to access than lowmem.
- LowTotal:
- LowFree: Lowmem is memory which can be used for everything that
- highmem can be used for, but it is also available for the
- kernel's use for its own data structures. Among many
- other things, it is where everything from the Slab is
- allocated. Bad things happen when you're out of lowmem.
- SwapTotal: total amount of swap space available
- SwapFree: Memory which has been evicted from RAM, and is temporarily
- on the disk
- Dirty: Memory which is waiting to get written back to the disk
- Writeback: Memory which is actively being written back to the disk
- AnonPages: Non-file backed pages mapped into userspace page tables
-AnonHugePages: Non-file backed huge pages mapped into userspace page tables
- Mapped: files which have been mmaped, such as libraries
- Slab: in-kernel data structures cache
-SReclaimable: Part of Slab, that might be reclaimed, such as caches
- SUnreclaim: Part of Slab, that cannot be reclaimed on memory pressure
- PageTables: amount of memory dedicated to the lowest level of page
- tables.
-NFS_Unstable: NFS pages sent to the server, but not yet committed to stable
- storage
- Bounce: Memory used for block device "bounce buffers"
-WritebackTmp: Memory used by FUSE for temporary writeback buffers
- CommitLimit: Based on the overcommit ratio ('vm.overcommit_ratio'),
- this is the total amount of memory currently available to
- be allocated on the system. This limit is only adhered to
- if strict overcommit accounting is enabled (mode 2 in
- 'vm.overcommit_memory').
- The CommitLimit is calculated with the following formula:
- CommitLimit = ('vm.overcommit_ratio' * Physical RAM) + Swap
- For example, on a system with 1G of physical RAM and 7G
- of swap with a `vm.overcommit_ratio` of 30 it would
- yield a CommitLimit of 7.3G.
- For more details, see the memory overcommit documentation
- in vm/overcommit-accounting.
-Committed_AS: The amount of memory presently allocated on the system.
- The committed memory is a sum of all of the memory which
- has been allocated by processes, even if it has not been
- "used" by them as of yet. A process which malloc()'s 1G
- of memory, but only touches 300M of it will only show up
- as using 300M of memory even if it has the address space
- allocated for the entire 1G. This 1G is memory which has
- been "committed" to by the VM and can be used at any time
- by the allocating application. With strict overcommit
- enabled on the system (mode 2 in 'vm.overcommit_memory'),
- allocations which would exceed the CommitLimit (detailed
- above) will not be permitted. This is useful if one needs
- to guarantee that processes will not fail due to lack of
- memory once that memory has been successfully allocated.
-VmallocTotal: total size of vmalloc memory area
- VmallocUsed: amount of vmalloc area which is used
-VmallocChunk: largest contiguous block of vmalloc area which is free
-
-..............................................................................
-
-vmallocinfo:
-
-Provides information about vmalloced/vmaped areas. One line per area,
-containing the virtual address range of the area, size in bytes,
-caller information of the creator, and optional information depending
-on the kind of area :
-
- pages=nr number of pages
- phys=addr if a physical address was specified
- ioremap I/O mapping (ioremap() and friends)
- vmalloc vmalloc() area
- vmap vmap()ed pages
- user VM_USERMAP area
- vpages buffer for pages pointers was vmalloced (huge area)
- N<node>=nr (Only on NUMA kernels)
- Number of pages allocated on memory node <node>
-
-> cat /proc/vmallocinfo
-0xffffc20000000000-0xffffc20000201000 2101248 alloc_large_system_hash+0x204 ...
- /0x2c0 pages=512 vmalloc N0=128 N1=128 N2=128 N3=128
-0xffffc20000201000-0xffffc20000302000 1052672 alloc_large_system_hash+0x204 ...
- /0x2c0 pages=256 vmalloc N0=64 N1=64 N2=64 N3=64
-0xffffc20000302000-0xffffc20000304000 8192 acpi_tb_verify_table+0x21/0x4f...
- phys=7fee8000 ioremap
-0xffffc20000304000-0xffffc20000307000 12288 acpi_tb_verify_table+0x21/0x4f...
- phys=7fee7000 ioremap
-0xffffc2000031d000-0xffffc2000031f000 8192 init_vdso_vars+0x112/0x210
-0xffffc2000031f000-0xffffc2000032b000 49152 cramfs_uncompress_init+0x2e ...
- /0x80 pages=11 vmalloc N0=3 N1=3 N2=2 N3=3
-0xffffc2000033a000-0xffffc2000033d000 12288 sys_swapon+0x640/0xac0 ...
- pages=2 vmalloc N1=2
-0xffffc20000347000-0xffffc2000034c000 20480 xt_alloc_table_info+0xfe ...
- /0x130 [x_tables] pages=4 vmalloc N0=4
-0xffffffffa0000000-0xffffffffa000f000 61440 sys_init_module+0xc27/0x1d00 ...
- pages=14 vmalloc N2=14
-0xffffffffa000f000-0xffffffffa0014000 20480 sys_init_module+0xc27/0x1d00 ...
- pages=4 vmalloc N1=4
-0xffffffffa0014000-0xffffffffa0017000 12288 sys_init_module+0xc27/0x1d00 ...
- pages=2 vmalloc N1=2
-0xffffffffa0017000-0xffffffffa0022000 45056 sys_init_module+0xc27/0x1d00 ...
- pages=10 vmalloc N0=10
-
-..............................................................................
-
-softirqs:
-
-Provides counts of softirq handlers serviced since boot time, for each cpu.
-
-> cat /proc/softirqs
- CPU0 CPU1 CPU2 CPU3
- HI: 0 0 0 0
- TIMER: 27166 27120 27097 27034
- NET_TX: 0 0 0 17
- NET_RX: 42 0 0 39
- BLOCK: 0 0 107 1121
- TASKLET: 0 0 0 290
- SCHED: 27035 26983 26971 26746
- HRTIMER: 0 0 0 0
- RCU: 1678 1769 2178 2250
-
-
-1.3 IDE devices in /proc/ide
-----------------------------
-
-The subdirectory /proc/ide contains information about all IDE devices of which
-the kernel is aware. There is one subdirectory for each IDE controller, the
-file drivers and a link for each IDE device, pointing to the device directory
-in the controller specific subtree.
-
-The file drivers contains general information about the drivers used for the
-IDE devices:
-
- > cat /proc/ide/drivers
- ide-cdrom version 4.53
- ide-disk version 1.08
-
-More detailed information can be found in the controller specific
-subdirectories. These are named ide0, ide1 and so on. Each of these
-directories contains the files shown in table 1-6.
-
-
-Table 1-6: IDE controller info in /proc/ide/ide?
-..............................................................................
- File Content
- channel IDE channel (0 or 1)
- config Configuration (only for PCI/IDE bridge)
- mate Mate name
- model Type/Chipset of IDE controller
-..............................................................................
-
-Each device connected to a controller has a separate subdirectory in the
-controllers directory. The files listed in table 1-7 are contained in these
-directories.
-
-
-Table 1-7: IDE device information
-..............................................................................
- File Content
- cache The cache
- capacity Capacity of the medium (in 512Byte blocks)
- driver driver and version
- geometry physical and logical geometry
- identify device identify block
- media media type
- model device identifier
- settings device setup
- smart_thresholds IDE disk management thresholds
- smart_values IDE disk management values
-..............................................................................
-
-The most interesting file is settings. This file contains a nice overview of
-the drive parameters:
-
- # cat /proc/ide/ide0/hda/settings
- name value min max mode
- ---- ----- --- --- ----
- bios_cyl 526 0 65535 rw
- bios_head 255 0 255 rw
- bios_sect 63 0 63 rw
- breada_readahead 4 0 127 rw
- bswap 0 0 1 r
- file_readahead 72 0 2097151 rw
- io_32bit 0 0 3 rw
- keepsettings 0 0 1 rw
- max_kb_per_request 122 1 127 rw
- multcount 0 0 8 rw
- nice1 1 0 1 rw
- nowerr 0 0 1 rw
- pio_mode write-only 0 255 w
- slow 0 0 1 rw
- unmaskirq 0 0 1 rw
- using_dma 0 0 1 rw
-
-
-1.4 Networking info in /proc/net
---------------------------------
-
-The subdirectory /proc/net follows the usual pattern. Table 1-8 shows the
-additional values you get for IP version 6 if you configure the kernel to
-support this. Table 1-9 lists the files and their meaning.
-
-
-Table 1-8: IPv6 info in /proc/net
-..............................................................................
- File Content
- udp6 UDP sockets (IPv6)
- tcp6 TCP sockets (IPv6)
- raw6 Raw device statistics (IPv6)
- igmp6 IP multicast addresses, which this host joined (IPv6)
- if_inet6 List of IPv6 interface addresses
- ipv6_route Kernel routing table for IPv6
- rt6_stats Global IPv6 routing tables statistics
- sockstat6 Socket statistics (IPv6)
- snmp6 Snmp data (IPv6)
-..............................................................................
-
-
-Table 1-9: Network info in /proc/net
-..............................................................................
- File Content
- arp Kernel ARP table
- dev network devices with statistics
- dev_mcast the Layer2 multicast groups a device is listening too
- (interface index, label, number of references, number of bound
- addresses).
- dev_stat network device status
- ip_fwchains Firewall chain linkage
- ip_fwnames Firewall chain names
- ip_masq Directory containing the masquerading tables
- ip_masquerade Major masquerading table
- netstat Network statistics
- raw raw device statistics
- route Kernel routing table
- rpc Directory containing rpc info
- rt_cache Routing cache
- snmp SNMP data
- sockstat Socket statistics
- tcp TCP sockets
- udp UDP sockets
- unix UNIX domain sockets
- wireless Wireless interface data (Wavelan etc)
- igmp IP multicast addresses, which this host joined
- psched Global packet scheduler parameters.
- netlink List of PF_NETLINK sockets
- ip_mr_vifs List of multicast virtual interfaces
- ip_mr_cache List of multicast routing cache
-..............................................................................
-
-You can use this information to see which network devices are available in
-your system and how much traffic was routed over those devices:
-
- > cat /proc/net/dev
- Inter-|Receive |[...
- face |bytes packets errs drop fifo frame compressed multicast|[...
- lo: 908188 5596 0 0 0 0 0 0 [...
- ppp0:15475140 20721 410 0 0 410 0 0 [...
- eth0: 614530 7085 0 0 0 0 0 1 [...
-
- ...] Transmit
- ...] bytes packets errs drop fifo colls carrier compressed
- ...] 908188 5596 0 0 0 0 0 0
- ...] 1375103 17405 0 0 0 0 0 0
- ...] 1703981 5535 0 0 0 3 0 0
-
-In addition, each Channel Bond interface has its own directory. For
-example, the bond0 device will have a directory called /proc/net/bond0/.
-It will contain information that is specific to that bond, such as the
-current slaves of the bond, the link status of the slaves, and how
-many times the slaves link has failed.
-
-1.5 SCSI info
--------------
-
-If you have a SCSI host adapter in your system, you'll find a subdirectory
-named after the driver for this adapter in /proc/scsi. You'll also see a list
-of all recognized SCSI devices in /proc/scsi:
-
- >cat /proc/scsi/scsi
- Attached devices:
- Host: scsi0 Channel: 00 Id: 00 Lun: 00
- Vendor: IBM Model: DGHS09U Rev: 03E0
- Type: Direct-Access ANSI SCSI revision: 03
- Host: scsi0 Channel: 00 Id: 06 Lun: 00
- Vendor: PIONEER Model: CD-ROM DR-U06S Rev: 1.04
- Type: CD-ROM ANSI SCSI revision: 02
-
-
-The directory named after the driver has one file for each adapter found in
-the system. These files contain information about the controller, including
-the used IRQ and the IO address range. The amount of information shown is
-dependent on the adapter you use. The example shows the output for an Adaptec
-AHA-2940 SCSI adapter:
-
- > cat /proc/scsi/aic7xxx/0
-
- Adaptec AIC7xxx driver version: 5.1.19/3.2.4
- Compile Options:
- TCQ Enabled By Default : Disabled
- AIC7XXX_PROC_STATS : Disabled
- AIC7XXX_RESET_DELAY : 5
- Adapter Configuration:
- SCSI Adapter: Adaptec AHA-294X Ultra SCSI host adapter
- Ultra Wide Controller
- PCI MMAPed I/O Base: 0xeb001000
- Adapter SEEPROM Config: SEEPROM found and used.
- Adaptec SCSI BIOS: Enabled
- IRQ: 10
- SCBs: Active 0, Max Active 2,
- Allocated 15, HW 16, Page 255
- Interrupts: 160328
- BIOS Control Word: 0x18b6
- Adapter Control Word: 0x005b
- Extended Translation: Enabled
- Disconnect Enable Flags: 0xffff
- Ultra Enable Flags: 0x0001
- Tag Queue Enable Flags: 0x0000
- Ordered Queue Tag Flags: 0x0000
- Default Tag Queue Depth: 8
- Tagged Queue By Device array for aic7xxx host instance 0:
- {255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255}
- Actual queue depth per device for aic7xxx host instance 0:
- {1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1}
- Statistics:
- (scsi0:0:0:0)
- Device using Wide/Sync transfers at 40.0 MByte/sec, offset 8
- Transinfo settings: current(12/8/1/0), goal(12/8/1/0), user(12/15/1/0)
- Total transfers 160151 (74577 reads and 85574 writes)
- (scsi0:0:6:0)
- Device using Narrow/Sync transfers at 5.0 MByte/sec, offset 15
- Transinfo settings: current(50/15/0/0), goal(50/15/0/0), user(50/15/0/0)
- Total transfers 0 (0 reads and 0 writes)
-
-
-1.6 Parallel port info in /proc/parport
----------------------------------------
-
-The directory /proc/parport contains information about the parallel ports of
-your system. It has one subdirectory for each port, named after the port
-number (0,1,2,...).
-
-These directories contain the four files shown in Table 1-10.
-
-
-Table 1-10: Files in /proc/parport
-..............................................................................
- File Content
- autoprobe Any IEEE-1284 device ID information that has been acquired.
- devices list of the device drivers using that port. A + will appear by the
- name of the device currently using the port (it might not appear
- against any).
- hardware Parallel port's base address, IRQ line and DMA channel.
- irq IRQ that parport is using for that port. This is in a separate
- file to allow you to alter it by writing a new value in (IRQ
- number or none).
-..............................................................................
-
-1.7 TTY info in /proc/tty
--------------------------
-
-Information about the available and actually used tty's can be found in the
-directory /proc/tty.You'll find entries for drivers and line disciplines in
-this directory, as shown in Table 1-11.
-
-
-Table 1-11: Files in /proc/tty
-..............................................................................
- File Content
- drivers list of drivers and their usage
- ldiscs registered line disciplines
- driver/serial usage statistic and status of single tty lines
-..............................................................................
-
-To see which tty's are currently in use, you can simply look into the file
-/proc/tty/drivers:
-
- > cat /proc/tty/drivers
- pty_slave /dev/pts 136 0-255 pty:slave
- pty_master /dev/ptm 128 0-255 pty:master
- pty_slave /dev/ttyp 3 0-255 pty:slave
- pty_master /dev/pty 2 0-255 pty:master
- serial /dev/cua 5 64-67 serial:callout
- serial /dev/ttyS 4 64-67 serial
- /dev/tty0 /dev/tty0 4 0 system:vtmaster
- /dev/ptmx /dev/ptmx 5 2 system
- /dev/console /dev/console 5 1 system:console
- /dev/tty /dev/tty 5 0 system:/dev/tty
- unknown /dev/tty 4 1-63 console
-
-
-1.8 Miscellaneous kernel statistics in /proc/stat
--------------------------------------------------
-
-Various pieces of information about kernel activity are available in the
-/proc/stat file. All of the numbers reported in this file are aggregates
-since the system first booted. For a quick look, simply cat the file:
-
- > cat /proc/stat
- cpu 2255 34 2290 22625563 6290 127 456 0 0
- cpu0 1132 34 1441 11311718 3675 127 438 0 0
- cpu1 1123 0 849 11313845 2614 0 18 0 0
- intr 114930548 113199788 3 0 5 263 0 4 [... lots more numbers ...]
- ctxt 1990473
- btime 1062191376
- processes 2915
- procs_running 1
- procs_blocked 0
- softirq 183433 0 21755 12 39 1137 231 21459 2263
-
-The very first "cpu" line aggregates the numbers in all of the other "cpuN"
-lines. These numbers identify the amount of time the CPU has spent performing
-different kinds of work. Time units are in USER_HZ (typically hundredths of a
-second). The meanings of the columns are as follows, from left to right:
-
-- user: normal processes executing in user mode
-- nice: niced processes executing in user mode
-- system: processes executing in kernel mode
-- idle: twiddling thumbs
-- iowait: waiting for I/O to complete
-- irq: servicing interrupts
-- softirq: servicing softirqs
-- steal: involuntary wait
-- guest: running a normal guest
-- guest_nice: running a niced guest
-
-The "intr" line gives counts of interrupts serviced since boot time, for each
-of the possible system interrupts. The first column is the total of all
-interrupts serviced; each subsequent column is the total for that particular
-interrupt.
-
-The "ctxt" line gives the total number of context switches across all CPUs.
-
-The "btime" line gives the time at which the system booted, in seconds since
-the Unix epoch.
-
-The "processes" line gives the number of processes and threads created, which
-includes (but is not limited to) those created by calls to the fork() and
-clone() system calls.
-
-The "procs_running" line gives the total number of threads that are
-running or ready to run (i.e., the total number of runnable threads).
-
-The "procs_blocked" line gives the number of processes currently blocked,
-waiting for I/O to complete.
-
-The "softirq" line gives counts of softirqs serviced since boot time, for each
-of the possible system softirqs. The first column is the total of all
-softirqs serviced; each subsequent column is the total for that particular
-softirq.
-
-
-1.9 Ext4 file system parameters
-------------------------------
-
-Information about mounted ext4 file systems can be found in
-/proc/fs/ext4. Each mounted filesystem will have a directory in
-/proc/fs/ext4 based on its device name (i.e., /proc/fs/ext4/hdc or
-/proc/fs/ext4/dm-0). The files in each per-device directory are shown
-in Table 1-12, below.
-
-Table 1-12: Files in /proc/fs/ext4/<devname>
-..............................................................................
- File Content
- mb_groups details of multiblock allocator buddy cache of free blocks
-..............................................................................
-
-2.0 /proc/consoles
-------------------
-Shows registered system console lines.
-
-To see which character device lines are currently used for the system console
-/dev/console, you may simply look into the file /proc/consoles:
-
- > cat /proc/consoles
- tty0 -WU (ECp) 4:7
- ttyS0 -W- (Ep) 4:64
-
-The columns are:
-
- device name of the device
- operations R = can do read operations
- W = can do write operations
- U = can do unblank
- flags E = it is enabled
- C = it is preferred console
- B = it is primary boot console
- p = it is used for printk buffer
- b = it is not a TTY but a Braille device
- a = it is safe to use when cpu is offline
- major:minor major and minor number of the device separated by a colon
-
-------------------------------------------------------------------------------
-Summary
-------------------------------------------------------------------------------
-The /proc file system serves information about the running system. It not only
-allows access to process data but also allows you to request the kernel status
-by reading files in the hierarchy.
-
-The directory structure of /proc reflects the types of information and makes
-it easy, if not obvious, where to look for specific data.
-------------------------------------------------------------------------------
-
-------------------------------------------------------------------------------
-CHAPTER 2: MODIFYING SYSTEM PARAMETERS
-------------------------------------------------------------------------------
-
-------------------------------------------------------------------------------
-In This Chapter
-------------------------------------------------------------------------------
-* Modifying kernel parameters by writing into files found in /proc/sys
-* Exploring the files which modify certain parameters
-* Review of the /proc/sys file tree
-------------------------------------------------------------------------------
-
-
-A very interesting part of /proc is the directory /proc/sys. This is not only
-a source of information, it also allows you to change parameters within the
-kernel. Be very careful when attempting this. You can optimize your system,
-but you can also cause it to crash. Never alter kernel parameters on a
-production system. Set up a development machine and test to make sure that
-everything works the way you want it to. You may have no alternative but to
-reboot the machine once an error has been made.
-
-To change a value, simply echo the new value into the file. An example is
-given below in the section on the file system data. You need to be root to do
-this. You can create your own boot script to perform this every time your
-system boots.
-
-The files in /proc/sys can be used to fine tune and monitor miscellaneous and
-general things in the operation of the Linux kernel. Since some of the files
-can inadvertently disrupt your system, it is advisable to read both
-documentation and source before actually making adjustments. In any case, be
-very careful when writing to any of these files. The entries in /proc may
-change slightly between the 2.1.* and the 2.2 kernel, so if there is any doubt
-review the kernel documentation in the directory /usr/src/linux/Documentation.
-This chapter is heavily based on the documentation included in the pre 2.2
-kernels, and became part of it in version 2.2.1 of the Linux kernel.
-
-Please see: Documentation/sysctl/ directory for descriptions of these
-entries.
-
-------------------------------------------------------------------------------
-Summary
-------------------------------------------------------------------------------
-Certain aspects of kernel behavior can be modified at runtime, without the
-need to recompile the kernel, or even to reboot the system. The files in the
-/proc/sys tree can not only be read, but also modified. You can use the echo
-command to write value into these files, thereby changing the default settings
-of the kernel.
-------------------------------------------------------------------------------
-
-------------------------------------------------------------------------------
-CHAPTER 3: PER-PROCESS PARAMETERS
-------------------------------------------------------------------------------
-
-3.1 /proc/<pid>/oom_adj & /proc/<pid>/oom_score_adj- Adjust the oom-killer score
---------------------------------------------------------------------------------
-
-These file can be used to adjust the badness heuristic used to select which
-process gets killed in out of memory conditions.
-
-The badness heuristic assigns a value to each candidate task ranging from 0
-(never kill) to 1000 (always kill) to determine which process is targeted. The
-units are roughly a proportion along that range of allowed memory the process
-may allocate from based on an estimation of its current memory and swap use.
-For example, if a task is using all allowed memory, its badness score will be
-1000. If it is using half of its allowed memory, its score will be 500.
-
-There is an additional factor included in the badness score: root
-processes are given 3% extra memory over other tasks.
-
-The amount of "allowed" memory depends on the context in which the oom killer
-was called. If it is due to the memory assigned to the allocating task's cpuset
-being exhausted, the allowed memory represents the set of mems assigned to that
-cpuset. If it is due to a mempolicy's node(s) being exhausted, the allowed
-memory represents the set of mempolicy nodes. If it is due to a memory
-limit (or swap limit) being reached, the allowed memory is that configured
-limit. Finally, if it is due to the entire system being out of memory, the
-allowed memory represents all allocatable resources.
-
-The value of /proc/<pid>/oom_score_adj is added to the badness score before it
-is used to determine which task to kill. Acceptable values range from -1000
-(OOM_SCORE_ADJ_MIN) to +1000 (OOM_SCORE_ADJ_MAX). This allows userspace to
-polarize the preference for oom killing either by always preferring a certain
-task or completely disabling it. The lowest possible value, -1000, is
-equivalent to disabling oom killing entirely for that task since it will always
-report a badness score of 0.
-
-Consequently, it is very simple for userspace to define the amount of memory to
-consider for each task. Setting a /proc/<pid>/oom_score_adj value of +500, for
-example, is roughly equivalent to allowing the remainder of tasks sharing the
-same system, cpuset, mempolicy, or memory controller resources to use at least
-50% more memory. A value of -500, on the other hand, would be roughly
-equivalent to discounting 50% of the task's allowed memory from being considered
-as scoring against the task.
-
-For backwards compatibility with previous kernels, /proc/<pid>/oom_adj may also
-be used to tune the badness score. Its acceptable values range from -16
-(OOM_ADJUST_MIN) to +15 (OOM_ADJUST_MAX) and a special value of -17
-(OOM_DISABLE) to disable oom killing entirely for that task. Its value is
-scaled linearly with /proc/<pid>/oom_score_adj.
-
-Writing to /proc/<pid>/oom_score_adj or /proc/<pid>/oom_adj will change the
-other with its scaled value.
-
-The value of /proc/<pid>/oom_score_adj may be reduced no lower than the last
-value set by a CAP_SYS_RESOURCE process. To reduce the value any lower
-requires CAP_SYS_RESOURCE.
-
-NOTICE: /proc/<pid>/oom_adj is deprecated and will be removed, please see
-Documentation/feature-removal-schedule.txt.
-
-Caveat: when a parent task is selected, the oom killer will sacrifice any first
-generation children with separate address spaces instead, if possible. This
-avoids servers and important system daemons from being killed and loses the
-minimal amount of work.
-
-
-3.2 /proc/<pid>/oom_score - Display current oom-killer score
--------------------------------------------------------------
-
-This file can be used to check the current score used by the oom-killer is for
-any given <pid>. Use it together with /proc/<pid>/oom_adj to tune which
-process should be killed in an out-of-memory situation.
-
-
-3.3 /proc/<pid>/io - Display the IO accounting fields
--------------------------------------------------------
-
-This file contains IO statistics for each running process
-
-Example
--------
-
-test:/tmp # dd if=/dev/zero of=/tmp/test.dat &
-[1] 3828
-
-test:/tmp # cat /proc/3828/io
-rchar: 323934931
-wchar: 323929600
-syscr: 632687
-syscw: 632675
-read_bytes: 0
-write_bytes: 323932160
-cancelled_write_bytes: 0
-
-
-Description
------------
-
-rchar
------
-
-I/O counter: chars read
-The number of bytes which this task has caused to be read from storage. This
-is simply the sum of bytes which this process passed to read() and pread().
-It includes things like tty IO and it is unaffected by whether or not actual
-physical disk IO was required (the read might have been satisfied from
-pagecache)
-
-
-wchar
------
-
-I/O counter: chars written
-The number of bytes which this task has caused, or shall cause to be written
-to disk. Similar caveats apply here as with rchar.
-
-
-syscr
------
-
-I/O counter: read syscalls
-Attempt to count the number of read I/O operations, i.e. syscalls like read()
-and pread().
-
-
-syscw
------
-
-I/O counter: write syscalls
-Attempt to count the number of write I/O operations, i.e. syscalls like
-write() and pwrite().
-
-
-read_bytes
-----------
-
-I/O counter: bytes read
-Attempt to count the number of bytes which this process really did cause to
-be fetched from the storage layer. Done at the submit_bio() level, so it is
-accurate for block-backed filesystems. <please add status regarding NFS and
-CIFS at a later time>
-
-
-write_bytes
------------
-
-I/O counter: bytes written
-Attempt to count the number of bytes which this process caused to be sent to
-the storage layer. This is done at page-dirtying time.
-
-
-cancelled_write_bytes
----------------------
-
-The big inaccuracy here is truncate. If a process writes 1MB to a file and
-then deletes the file, it will in fact perform no writeout. But it will have
-been accounted as having caused 1MB of write.
-In other words: The number of bytes which this process caused to not happen,
-by truncating pagecache. A task can cause "negative" IO too. If this task
-truncates some dirty pagecache, some IO which another task has been accounted
-for (in its write_bytes) will not be happening. We _could_ just subtract that
-from the truncating task's write_bytes, but there is information loss in doing
-that.
-
-
-Note
-----
-
-At its current implementation state, this is a bit racy on 32-bit machines: if
-process A reads process B's /proc/pid/io while process B is updating one of
-those 64-bit counters, process A could see an intermediate result.
-
-
-More information about this can be found within the taskstats documentation in
-Documentation/accounting.
-
-3.4 /proc/<pid>/coredump_filter - Core dump filtering settings
----------------------------------------------------------------
-When a process is dumped, all anonymous memory is written to a core file as
-long as the size of the core file isn't limited. But sometimes we don't want
-to dump some memory segments, for example, huge shared memory. Conversely,
-sometimes we want to save file-backed memory segments into a core file, not
-only the individual files.
-
-/proc/<pid>/coredump_filter allows you to customize which memory segments
-will be dumped when the <pid> process is dumped. coredump_filter is a bitmask
-of memory types. If a bit of the bitmask is set, memory segments of the
-corresponding memory type are dumped, otherwise they are not dumped.
-
-The following 7 memory types are supported:
- - (bit 0) anonymous private memory
- - (bit 1) anonymous shared memory
- - (bit 2) file-backed private memory
- - (bit 3) file-backed shared memory
- - (bit 4) ELF header pages in file-backed private memory areas (it is
- effective only if the bit 2 is cleared)
- - (bit 5) hugetlb private memory
- - (bit 6) hugetlb shared memory
-
- Note that MMIO pages such as frame buffer are never dumped and vDSO pages
- are always dumped regardless of the bitmask status.
-
- Note bit 0-4 doesn't effect any hugetlb memory. hugetlb memory are only
- effected by bit 5-6.
-
-Default value of coredump_filter is 0x23; this means all anonymous memory
-segments and hugetlb private memory are dumped.
-
-If you don't want to dump all shared memory segments attached to pid 1234,
-write 0x21 to the process's proc file.
-
- $ echo 0x21 > /proc/1234/coredump_filter
-
-When a new process is created, the process inherits the bitmask status from its
-parent. It is useful to set up coredump_filter before the program runs.
-For example:
-
- $ echo 0x7 > /proc/self/coredump_filter
- $ ./some_program
-
-3.5 /proc/<pid>/mountinfo - Information about mounts
---------------------------------------------------------
-
-This file contains lines of the form:
-
-36 35 98:0 /mnt1 /mnt2 rw,noatime master:1 - ext3 /dev/root rw,errors=continue
-(1)(2)(3) (4) (5) (6) (7) (8) (9) (10) (11)
-
-(1) mount ID: unique identifier of the mount (may be reused after umount)
-(2) parent ID: ID of parent (or of self for the top of the mount tree)
-(3) major:minor: value of st_dev for files on filesystem
-(4) root: root of the mount within the filesystem
-(5) mount point: mount point relative to the process's root
-(6) mount options: per mount options
-(7) optional fields: zero or more fields of the form "tag[:value]"
-(8) separator: marks the end of the optional fields
-(9) filesystem type: name of filesystem of the form "type[.subtype]"
-(10) mount source: filesystem specific information or "none"
-(11) super options: per super block options
-
-Parsers should ignore all unrecognised optional fields. Currently the
-possible optional fields are:
-
-shared:X mount is shared in peer group X
-master:X mount is slave to peer group X
-propagate_from:X mount is slave and receives propagation from peer group X (*)
-unbindable mount is unbindable
-
-(*) X is the closest dominant peer group under the process's root. If
-X is the immediate master of the mount, or if there's no dominant peer
-group under the same root, then only the "master:X" field is present
-and not the "propagate_from:X" field.
-
-For more information on mount propagation see:
-
- Documentation/filesystems/sharedsubtree.txt
-
-
-3.6 /proc/<pid>/comm & /proc/<pid>/task/<tid>/comm
---------------------------------------------------------
-These files provide a method to access a tasks comm value. It also allows for
-a task to set its own or one of its thread siblings comm value. The comm value
-is limited in size compared to the cmdline value, so writing anything longer
-then the kernel's TASK_COMM_LEN (currently 16 chars) will result in a truncated
-comm value.
-
-
-3.7 /proc/<pid>/task/<tid>/children - Information about task children
--------------------------------------------------------------------------
-This file provides a fast way to retrieve first level children pids
-of a task pointed by <pid>/<tid> pair. The format is a space separated
-stream of pids.
-
-Note the "first level" here -- if a child has own children they will
-not be listed here, one needs to read /proc/<children-pid>/task/<tid>/children
-to obtain the descendants.
-
-Since this interface is intended to be fast and cheap it doesn't
-guarantee to provide precise results and some children might be
-skipped, especially if they've exited right after we printed their
-pids, so one need to either stop or freeze processes being inspected
-if precise results are needed.
-
-
-------------------------------------------------------------------------------
-Configuring procfs
-------------------------------------------------------------------------------
-
-4.1 Mount options
----------------------
-
-The following mount options are supported:
-
- hidepid= Set /proc/<pid>/ access mode.
- gid= Set the group authorized to learn processes information.
-
-hidepid=0 means classic mode - everybody may access all /proc/<pid>/ directories
-(default).
-
-hidepid=1 means users may not access any /proc/<pid>/ directories but their
-own. Sensitive files like cmdline, sched*, status are now protected against
-other users. This makes it impossible to learn whether any user runs
-specific program (given the program doesn't reveal itself by its behaviour).
-As an additional bonus, as /proc/<pid>/cmdline is unaccessible for other users,
-poorly written programs passing sensitive information via program arguments are
-now protected against local eavesdroppers.
-
-hidepid=2 means hidepid=1 plus all /proc/<pid>/ will be fully invisible to other
-users. It doesn't mean that it hides a fact whether a process with a specific
-pid value exists (it can be learned by other means, e.g. by "kill -0 $PID"),
-but it hides process' uid and gid, which may be learned by stat()'ing
-/proc/<pid>/ otherwise. It greatly complicates an intruder's task of gathering
-information about running processes, whether some daemon runs with elevated
-privileges, whether other user runs some sensitive program, whether other users
-run any program at all, etc.
-
-gid= defines a group authorized to learn processes information otherwise
-prohibited by hidepid=. If you use some daemon like identd which needs to learn
-information about processes information, just add identd to this group.