diff options
| author | ddomingo <ddomingo@redhat.com> | 2008-10-13 09:36:52 +1000 |
|---|---|---|
| committer | ddomingo <ddomingo@redhat.com> | 2008-10-13 09:36:52 +1000 |
| commit | 30eb88b11b2a1438a400f0c2b1118d600010df27 (patch) | |
| tree | 53bbae5deeb11a010b0d1f99f9de56559401ae5b /doc/SystemTap_Beginners_Guide | |
| parent | e2607b19ce56830d64affed6a8ab169697bf2ccf (diff) | |
| download | systemtap-steved-30eb88b11b2a1438a400f0c2b1118d600010df27.tar.gz systemtap-steved-30eb88b11b2a1438a400f0c2b1118d600010df27.tar.xz systemtap-steved-30eb88b11b2a1438a400f0c2b1118d600010df27.zip | |
added Useful_Scripts-kernelprofiling.xml
Diffstat (limited to 'doc/SystemTap_Beginners_Guide')
3 files changed, 113 insertions, 1 deletions
diff --git a/doc/SystemTap_Beginners_Guide/en-US/Useful_Scripts-functioncalls.xml b/doc/SystemTap_Beginners_Guide/en-US/Useful_Scripts-functioncalls.xml index 76a2fad9..4ebfa6fa 100644 --- a/doc/SystemTap_Beginners_Guide/en-US/Useful_Scripts-functioncalls.xml +++ b/doc/SystemTap_Beginners_Guide/en-US/Useful_Scripts-functioncalls.xml @@ -22,7 +22,7 @@ no script in examples <title>countcalls.stp</title> <para> <programlisting> -probe kernel.function(@1) { # probe every function in any C file under mm/ +probe kernel.function(@1) { # probe function passed as argument from stdin called[probefunc()] <<< 1 # add a count efficiently } global called diff --git a/doc/SystemTap_Beginners_Guide/en-US/Useful_Scripts-kernelprofiling.xml b/doc/SystemTap_Beginners_Guide/en-US/Useful_Scripts-kernelprofiling.xml new file mode 100644 index 00000000..0fd172dd --- /dev/null +++ b/doc/SystemTap_Beginners_Guide/en-US/Useful_Scripts-kernelprofiling.xml @@ -0,0 +1,111 @@ +<?xml version='1.0'?> +<!DOCTYPE section PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN" "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [ +]> + + + <section id="kernelprofsect"> + <title>Kernel Profiling</title> + + +<remark> + WAR STORY: Kernel Profiling http://sourceware.org/systemtap/wiki/WSKernelProfile?highlight=((WarStories)) +</remark> + +<remark> + http://sourceware.org/systemtap/examples/process/pf2.stp +</remark> + + +<para>In <xref linkend="countcallssect"/>, you can revise the wildcards used in the probe to target <emphasis>all</emphasis> kernel functions. This can be useful if you are interested in indentifying what the kernel is performing over a specific time period.</para> + +<para>However, doing so can cause considerable stress on the machine. In addition, this does not provide any indication of whether a specific function is being called too often during small time increments.</para> + +<para>This section describes how to profile the kernel properly. <xref linkend="kernelprof"/> does this by providing a list of the top ten kernel functions called within a specific time period, and how many times each function was called during that time.</para> + + +<formalpara id="kernelprof"> + <title>kernelprof.stp</title> +<para> +<programlisting> +#! /usr/bin/env stap
+
+global profile, pcount
+probe timer.profile {
+pcount <<< 1
+ fn = probefunc ()
+ if (fn != "") profile[fn] <<< 1
+}
+probe timer.ms(5000) {
+ printf ("\n--- %d samples recorded:\n", @count(pcount))
+ foreach (f in profile- limit 10) {
+ printf ("%-30s\t%6d\n", f, @count(profile[f]))
+ }
+ delete profile
+ delete pcount
+}
+ +</programlisting> +</para> +</formalpara> + +<para><xref linkend="kernelprof"/> records and outputs kernel functions called every 5 seconds. You can change this setting by editing <command>probe timer.ms(5000)</command> accordingly. <xref linkend="kernelprofoutput"/> contains an excerpt of the output over a 20-second period:</para> + +<example id="kernelprofoutput"> + <title><xref linkend="kernelprof"/> Sample Output</title> +<screen> +[...] +--- 10002 samples recorded:
+sys_recvfrom 1
+memmove 1
+__copy_from_user_ll 17
+__copy_to_user_ll 15
+mwait_idle 5868
+link_path_walk 1
+kfree 1
+fget_light 1
+audit_syscall_exit 1
+__d_lookup 1
+ +--- 10002 samples recorded:
+sysfs_read_file 1
+free_poll_entry 1
+syscall_exit_work 1
+profile_hit 1
+do_page_fault 2
+_read_lock 3
+kmap_atomic 4
+strncpy_from_user 1
+find_vma_prepare 1
+__copy_from_user_ll 12
+ +--- 10000 samples recorded:
+system_call 4
+unix_stream_sendmsg 1
+__d_path 1
+do_page_fault 2
+kmap_atomic 1
+find_vma 1
+__copy_to_user_ll 16
+__copy_from_user_ll 10
+mwait_idle 5759
+memcpy_fromiovec 1
+ +--- 10004 samples recorded:
+syscall_exit 1
+__d_path 1
+fput 2
+do_page_fault 4
+strncpy_from_user 1
+may_open 1
+ide_outb 1
+ide_outsw 1
+__copy_to_user_ll 11
+__copy_from_user_ll 14
+[...] +</screen> +</example> + +<para><xref linkend="kernelprof"/> allows you to identify interesting kernel-specific performance facts about the system, such as kernel-intensive workloads and idle times (in this case, <command>mwait_idle</command>. Note that <xref linkend="kernelprof"/> does not count user-space functions, although it counts all kernel functions as part of the sample (even if the script cannot identify from which specific kernel function a call originated.</para> + + </section> + diff --git a/doc/SystemTap_Beginners_Guide/en-US/Useful_SystemTap_Scripts.xml b/doc/SystemTap_Beginners_Guide/en-US/Useful_SystemTap_Scripts.xml index fb2dba54..03cb6b40 100644 --- a/doc/SystemTap_Beginners_Guide/en-US/Useful_SystemTap_Scripts.xml +++ b/doc/SystemTap_Beginners_Guide/en-US/Useful_SystemTap_Scripts.xml @@ -29,6 +29,7 @@ <xi:include href="Useful_Scripts-inodewatch.xml" xmlns:xi="http://www.w3.org/2001/XInclude" /> <xi:include href="Useful_Scripts-inodewatch2.xml" xmlns:xi="http://www.w3.org/2001/XInclude" /> <xi:include href="Useful_Scripts-functioncalls.xml" xmlns:xi="http://www.w3.org/2001/XInclude" /> + <xi:include href="Useful_Scripts-kernelprofiling.xml" xmlns:xi="http://www.w3.org/2001/XInclude" /> <xi:include href="Useful_Scripts-futexes.xml" xmlns:xi="http://www.w3.org/2001/XInclude" /> <!-- <xi:include href="Useful_Scripts-Network.xml" xmlns:xi="http://www.w3.org/2001/XInclude" /> <xi:include href="Useful_Scripts-Signals.xml" xmlns:xi="http://www.w3.org/2001/XInclude" /> |