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Diffstat (limited to 'src/tools/perf/Documentation/examples.txt')
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diff --git a/src/tools/perf/Documentation/examples.txt b/src/tools/perf/Documentation/examples.txt deleted file mode 100644 index a4e3921..0000000 --- a/src/tools/perf/Documentation/examples.txt +++ /dev/null @@ -1,225 +0,0 @@ - - ------------------------------ - ****** perf by examples ****** - ------------------------------ - -[ From an e-mail by Ingo Molnar, http://lkml.org/lkml/2009/8/4/346 ] - - -First, discovery/enumeration of available counters can be done via -'perf list': - -titan:~> perf list - [...] - kmem:kmalloc [Tracepoint event] - kmem:kmem_cache_alloc [Tracepoint event] - kmem:kmalloc_node [Tracepoint event] - kmem:kmem_cache_alloc_node [Tracepoint event] - kmem:kfree [Tracepoint event] - kmem:kmem_cache_free [Tracepoint event] - kmem:mm_page_free [Tracepoint event] - kmem:mm_page_free_batched [Tracepoint event] - kmem:mm_page_alloc [Tracepoint event] - kmem:mm_page_alloc_zone_locked [Tracepoint event] - kmem:mm_page_pcpu_drain [Tracepoint event] - kmem:mm_page_alloc_extfrag [Tracepoint event] - -Then any (or all) of the above event sources can be activated and -measured. For example the page alloc/free properties of a 'hackbench -run' are: - - titan:~> perf stat -e kmem:mm_page_pcpu_drain -e kmem:mm_page_alloc - -e kmem:mm_page_free_batched -e kmem:mm_page_free ./hackbench 10 - Time: 0.575 - - Performance counter stats for './hackbench 10': - - 13857 kmem:mm_page_pcpu_drain - 27576 kmem:mm_page_alloc - 6025 kmem:mm_page_free_batched - 20934 kmem:mm_page_free - - 0.613972165 seconds time elapsed - -You can observe the statistical properties as well, by using the -'repeat the workload N times' feature of perf stat: - - titan:~> perf stat --repeat 5 -e kmem:mm_page_pcpu_drain -e - kmem:mm_page_alloc -e kmem:mm_page_free_batched -e - kmem:mm_page_free ./hackbench 10 - Time: 0.627 - Time: 0.644 - Time: 0.564 - Time: 0.559 - Time: 0.626 - - Performance counter stats for './hackbench 10' (5 runs): - - 12920 kmem:mm_page_pcpu_drain ( +- 3.359% ) - 25035 kmem:mm_page_alloc ( +- 3.783% ) - 6104 kmem:mm_page_free_batched ( +- 0.934% ) - 18376 kmem:mm_page_free ( +- 4.941% ) - - 0.643954516 seconds time elapsed ( +- 2.363% ) - -Furthermore, these tracepoints can be used to sample the workload as -well. For example the page allocations done by a 'git gc' can be -captured the following way: - - titan:~/git> perf record -e kmem:mm_page_alloc -c 1 ./git gc - Counting objects: 1148, done. - Delta compression using up to 2 threads. - Compressing objects: 100% (450/450), done. - Writing objects: 100% (1148/1148), done. - Total 1148 (delta 690), reused 1148 (delta 690) - [ perf record: Captured and wrote 0.267 MB perf.data (~11679 samples) ] - -To check which functions generated page allocations: - - titan:~/git> perf report - # Samples: 10646 - # - # Overhead Command Shared Object - # ........ ............... .......................... - # - 23.57% git-repack /lib64/libc-2.5.so - 21.81% git /lib64/libc-2.5.so - 14.59% git ./git - 11.79% git-repack ./git - 7.12% git /lib64/ld-2.5.so - 3.16% git-repack /lib64/libpthread-2.5.so - 2.09% git-repack /bin/bash - 1.97% rm /lib64/libc-2.5.so - 1.39% mv /lib64/ld-2.5.so - 1.37% mv /lib64/libc-2.5.so - 1.12% git-repack /lib64/ld-2.5.so - 0.95% rm /lib64/ld-2.5.so - 0.90% git-update-serv /lib64/libc-2.5.so - 0.73% git-update-serv /lib64/ld-2.5.so - 0.68% perf /lib64/libpthread-2.5.so - 0.64% git-repack /usr/lib64/libz.so.1.2.3 - -Or to see it on a more finegrained level: - -titan:~/git> perf report --sort comm,dso,symbol -# Samples: 10646 -# -# Overhead Command Shared Object Symbol -# ........ ............... .......................... ...... -# - 9.35% git-repack ./git [.] insert_obj_hash - 9.12% git ./git [.] insert_obj_hash - 7.31% git /lib64/libc-2.5.so [.] memcpy - 6.34% git-repack /lib64/libc-2.5.so [.] _int_malloc - 6.24% git-repack /lib64/libc-2.5.so [.] memcpy - 5.82% git-repack /lib64/libc-2.5.so [.] __GI___fork - 5.47% git /lib64/libc-2.5.so [.] _int_malloc - 2.99% git /lib64/libc-2.5.so [.] memset - -Furthermore, call-graph sampling can be done too, of page -allocations - to see precisely what kind of page allocations there -are: - - titan:~/git> perf record -g -e kmem:mm_page_alloc -c 1 ./git gc - Counting objects: 1148, done. - Delta compression using up to 2 threads. - Compressing objects: 100% (450/450), done. - Writing objects: 100% (1148/1148), done. - Total 1148 (delta 690), reused 1148 (delta 690) - [ perf record: Captured and wrote 0.963 MB perf.data (~42069 samples) ] - - titan:~/git> perf report -g - # Samples: 10686 - # - # Overhead Command Shared Object - # ........ ............... .......................... - # - 23.25% git-repack /lib64/libc-2.5.so - | - |--50.00%-- _int_free - | - |--37.50%-- __GI___fork - | make_child - | - |--12.50%-- ptmalloc_unlock_all2 - | make_child - | - --6.25%-- __GI_strcpy - 21.61% git /lib64/libc-2.5.so - | - |--30.00%-- __GI_read - | | - | --83.33%-- git_config_from_file - | git_config - | | - [...] - -Or you can observe the whole system's page allocations for 10 -seconds: - -titan:~/git> perf stat -a -e kmem:mm_page_pcpu_drain -e -kmem:mm_page_alloc -e kmem:mm_page_free_batched -e -kmem:mm_page_free sleep 10 - - Performance counter stats for 'sleep 10': - - 171585 kmem:mm_page_pcpu_drain - 322114 kmem:mm_page_alloc - 73623 kmem:mm_page_free_batched - 254115 kmem:mm_page_free - - 10.000591410 seconds time elapsed - -Or observe how fluctuating the page allocations are, via statistical -analysis done over ten 1-second intervals: - - titan:~/git> perf stat --repeat 10 -a -e kmem:mm_page_pcpu_drain -e - kmem:mm_page_alloc -e kmem:mm_page_free_batched -e - kmem:mm_page_free sleep 1 - - Performance counter stats for 'sleep 1' (10 runs): - - 17254 kmem:mm_page_pcpu_drain ( +- 3.709% ) - 34394 kmem:mm_page_alloc ( +- 4.617% ) - 7509 kmem:mm_page_free_batched ( +- 4.820% ) - 25653 kmem:mm_page_free ( +- 3.672% ) - - 1.058135029 seconds time elapsed ( +- 3.089% ) - -Or you can annotate the recorded 'git gc' run on a per symbol basis -and check which instructions/source-code generated page allocations: - - titan:~/git> perf annotate __GI___fork - ------------------------------------------------ - Percent | Source code & Disassembly of libc-2.5.so - ------------------------------------------------ - : - : - : Disassembly of section .plt: - : Disassembly of section .text: - : - : 00000031a2e95560 <__fork>: - [...] - 0.00 : 31a2e95602: b8 38 00 00 00 mov $0x38,%eax - 0.00 : 31a2e95607: 0f 05 syscall - 83.42 : 31a2e95609: 48 3d 00 f0 ff ff cmp $0xfffffffffffff000,%rax - 0.00 : 31a2e9560f: 0f 87 4d 01 00 00 ja 31a2e95762 <__fork+0x202> - 0.00 : 31a2e95615: 85 c0 test %eax,%eax - -( this shows that 83.42% of __GI___fork's page allocations come from - the 0x38 system call it performs. ) - -etc. etc. - a lot more is possible. I could list a dozen of -other different usecases straight away - neither of which is -possible via /proc/vmstat. - -/proc/vmstat is not in the same league really, in terms of -expressive power of system analysis and performance -analysis. - -All that the above results needed were those new tracepoints -in include/tracing/events/kmem.h. - - Ingo - - |