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| -rw-r--r-- | doc/SystemTap_Beginners_Guide/en-US/Useful_Scripts-ioblktime.xml | 111 | ||||
| -rw-r--r-- | doc/SystemTap_Beginners_Guide/en-US/Useful_SystemTap_Scripts.xml | 2 |
2 files changed, 113 insertions, 0 deletions
diff --git a/doc/SystemTap_Beginners_Guide/en-US/Useful_Scripts-ioblktime.xml b/doc/SystemTap_Beginners_Guide/en-US/Useful_Scripts-ioblktime.xml new file mode 100644 index 00000000..e586d81a --- /dev/null +++ b/doc/SystemTap_Beginners_Guide/en-US/Useful_Scripts-ioblktime.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="ioblktimesect"> + <title>Periodically Print I/O Block Time</title> +<indexterm> +<primary>script examples</primary> +<secondary>monitoring I/O block time</secondary> +</indexterm> + +<indexterm> +<primary>examples of SystemTap scripts</primary> +<secondary>monitoring I/O block time</secondary> +</indexterm> + +<indexterm> +<primary>monitoring I/O block time</primary> +<secondary>examples of SystemTap scripts</secondary> +</indexterm> + +<indexterm> +<primary>I/O block time, monitoring</primary> +<secondary>examples of SystemTap scripts</secondary> +</indexterm> + +<indexterm> +<primary>printing I/O block time (periodically)</primary> +<secondary>examples of SystemTap scripts</secondary> +</indexterm> + + <para> + This section describes how to track the amount of time each block I/O requests spends + waiting for completion. This is useful in determining whether there are too many + outstanding block I/O operations at any given time. + </para> + +<formalpara id="ioblktime"> + <title>ioblktime.stp</title> +<para> +<programlisting> +<xi:include parse="text" href="extras/testsuite/systemtap.examples/io/ioblktime.stp" xmlns:xi="http://www.w3.org/2001/XInclude" /> +</programlisting> +</para> +</formalpara> + +<!-- <remark>what does $count do, specifically?</remark> --> + +<para> + <xref linkend="ioblktime"/> computes the average waiting time for block I/O per device, + and prints a list every 10 seconds. As always, you can revise this refresh rate by + editing the specified value in <command>probe timer.s(10), end {</command>. +</para> +<para> + In some cases, there can be too many outstanding block + I/O operations, at which point the script can exceed the default number of + <command>MAXMAPENTRIES</command>. <command>MAXMAPENTRIES</command> is the maximum number of + rows in an array if the array size is not specified explicitly when declared. If the script + exceeds the default <command>MAXMAPENTRIES</command> value of 2048, run the script again with + the <command>stap</command> option <command>-DMAXMAPENTRIES=10000</command>. +</para> + + +<example id="ioblktimeoutput"> + <title><xref linkend="ioblktime"/> Sample Output</title> +<screen> + device rw total (us) count avg (us)
+ sda W 9659 6 1609
+ dm-0 W 20278 6 3379
+ dm-0 R 20524 5 4104
+ sda R 19277 5 3855
+</screen> +</example> + +<para> + <xref linkend="ioblktimeoutput"/> displays the device name, operations performed + (<command>rw</command>), total wait time of all operations (<command>total(us)</command>), + number of operations (<command>count</command>), and average + wait time for all those operations (<command>avg (us)</command>). The times tallied by the + script are in microseconds. +</para> + +<!-- +global reads, writes, total_io + +probe kernel.function("vfs_read") { +reads[execname()] += $count +} + +probe kernel.function("vfs_write") { +writes[execname()] += $count +} + +# print top 10 IO processes every 5 seconds +probe timer.s(5) { +foreach (name in writes) +total_io[name] += writes[name] +foreach (name in reads) +total_io[name] += reads[name] +printf ("%16s\t%10s\t%10s\n", "Process", "KB Read", "KB Written") +foreach (name in total_io- limit 10) +printf("%16s\t%10d\t%10d\n", name, +reads[name]/1024, writes[name]/1024) +delete reads +delete writes +delete total_io +print("\n") +} +--> + +</section>
\ No newline at end of file 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 80e68770..4d999b53 100644 --- a/doc/SystemTap_Beginners_Guide/en-US/Useful_SystemTap_Scripts.xml +++ b/doc/SystemTap_Beginners_Guide/en-US/Useful_SystemTap_Scripts.xml @@ -56,6 +56,7 @@ <!-- <xi:include href="Useful_Scripts-Kernel.xml" xmlns:xi="http://www.w3.org/2001/XInclude" /> --> <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 condition="fedora" href="Useful_Scripts-ioblktime.xml" xmlns:xi="http://www.w3.org/2001/XInclude" /> </section> <section id="mainsect-profiling"> @@ -71,6 +72,7 @@ <!-- removed; handler function no longer working as expected <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" /> |