perf/Documentation/examples.txt

2 		------------------------------
4 		------------------------------
6 [ From an e-mail by Ingo Molnar, https://lore.kernel.org/lkml/20090804195717.GA5998@elte.hu ]
31  titan:~> perf stat -e kmem:mm_page_pcpu_drain -e kmem:mm_page_alloc
32  -e kmem:mm_page_free_batched -e kmem:mm_page_free ./hackbench 10
47  titan:~> perf stat --repeat 5 -e kmem:mm_page_pcpu_drain -e
48    kmem:mm_page_alloc -e kmem:mm_page_free_batched -e
58           12920  kmem:mm_page_pcpu_drain    ( +-   3.359% )
59           25035  kmem:mm_page_alloc         ( +-   3.783% )
60            6104  kmem:mm_page_free_batched  ( +-   0.934% )
61           18376  kmem:mm_page_free	    ( +-   4.941% )
63     0.643954516  seconds time elapsed   ( +-   2.363% )
69  titan:~/git> perf record -e kmem:mm_page_alloc -c 1 ./git gc
71  Delta compression using up to 2 threads.
75  [ perf record: Captured and wrote 0.267 MB perf.data (~11679 samples) ]
80  # Samples: 10646
85     23.57%       git-repack  /lib64/libc-2.5.so
86     21.81%              git  /lib64/libc-2.5.so
88     11.79%       git-repack  ./git
89      7.12%              git  /lib64/ld-2.5.so
90      3.16%       git-repack  /lib64/libpthread-2.5.so
91      2.09%       git-repack  /bin/bash
92      1.97%               rm  /lib64/libc-2.5.so
93      1.39%               mv  /lib64/ld-2.5.so
94      1.37%               mv  /lib64/libc-2.5.so
95      1.12%       git-repack  /lib64/ld-2.5.so
96      0.95%               rm  /lib64/ld-2.5.so
97      0.90%  git-update-serv  /lib64/libc-2.5.so
98      0.73%  git-update-serv  /lib64/ld-2.5.so
99      0.68%             perf  /lib64/libpthread-2.5.so
100      0.64%       git-repack  /usr/lib64/libz.so.1.2.3
104 titan:~/git> perf report --sort comm,dso,symbol
105 # Samples: 10646
110      9.35%       git-repack  ./git                       [.] insert_obj_hash
112      7.31%              git  /lib64/libc-2.5.so          [.] memcpy
113      6.34%       git-repack  /lib64/libc-2.5.so          [.] _int_malloc
114      6.24%       git-repack  /lib64/libc-2.5.so          [.] memcpy
115      5.82%       git-repack  /lib64/libc-2.5.so          [.] __GI___fork
116      5.47%              git  /lib64/libc-2.5.so          [.] _int_malloc
117      2.99%              git  /lib64/libc-2.5.so          [.] memset
119 Furthermore, call-graph sampling can be done too, of page
120 allocations - to see precisely what kind of page allocations there
123  titan:~/git> perf record -g -e kmem:mm_page_alloc -c 1 ./git gc
125  Delta compression using up to 2 threads.
129  [ perf record: Captured and wrote 0.963 MB perf.data (~42069 samples) ]
131  titan:~/git> perf report -g
132  # Samples: 10686
137     23.25%       git-repack  /lib64/libc-2.5.so
139                 |--50.00%-- _int_free
141                 |--37.50%-- __GI___fork
144                 |--12.50%-- ptmalloc_unlock_all2
147                  --6.25%-- __GI_strcpy
148     21.61%              git  /lib64/libc-2.5.so
150                 |--30.00%-- __GI_read
152                 |           --83.33%-- git_config_from_file
160 titan:~/git> perf stat -a -e kmem:mm_page_pcpu_drain -e
161 kmem:mm_page_alloc -e kmem:mm_page_free_batched -e
174 analysis done over ten 1-second intervals:
176  titan:~/git> perf stat --repeat 10 -a -e kmem:mm_page_pcpu_drain -e
177    kmem:mm_page_alloc -e kmem:mm_page_free_batched -e
182           17254  kmem:mm_page_pcpu_drain    ( +-   3.709% )
183           34394  kmem:mm_page_alloc         ( +-   4.617% )
184            7509  kmem:mm_page_free_batched  ( +-   4.820% )
185           25653  kmem:mm_page_free	    ( +-   3.672% )
187     1.058135029  seconds time elapsed   ( +-   3.089% )
190 and check which instructions/source-code generated page allocations:
193  ------------------------------------------------
194   Percent |      Source code & Disassembly of libc-2.5.so
195  ------------------------------------------------
212 etc. etc. - a lot more is possible. I could list a dozen of
213 other different usecases straight away - neither of which is