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Arnaldo Carvalho de Melo authored
So at the top we'll have two lines, like this, from 'perf report': # perf report --group --ignore-vmlinux ===================================================================================================== Samples: 46 of events 'cycles', 4000 Hz, Event count (approx.): 5154895 _raw_spin_lock_irqsave /proc/kcore Percent │ nop │ push %rbx 0.00 14.29 0.00 │ pushfq 9.09 0.00 0.00 │ pop %rax 9.09 0.00 20.00 │ nop │ mov %rax,%rbx │ cli 4.55 7.14 0.00 │ nop │ xor %eax,%eax │ mov $0x1,%edx │ lock cmpxchg %edx,(%rdi) 77.27 78.57 70.00 │ test %eax,%eax │ ↓ jne 2b │ mov %rbx,%rax 0.00 0.00 10.00 │ pop %rbx │ ← retq │2b: mov %eax,%esi │ → callq queued_spin_lock_slowpath │ mov %rbx,%rax │ pop %rbx Press 'h' for help on│key bindings ===================================================================================================== 9.09 + 9.09 + 4.55 + 77.27 = 100 14.29 + 7.14 + 78.57 = 100 20 + 70 + 10 = 100 We can do the math by using 't' to toggle from 'percent' to nr ===================================================================================================== Samples: 46 of events 'cycles', 4000 Hz, Event count (approx.): 5154895 _raw_spin_lock_irqsave /proc/kcore Period │ nop │ push %rbx 0 79273 0 │ pushfq 190455 0 0 │ pop %rax 198038 0 3045 │ nop │ mov %rax,%rbx │ cli 217233 32562 0 │ nop │ xor %eax,%eax │ mov $0x1,%edx │ lock cmpxchg %edx,(%rdi) 3421649 979174 28273 │ test %eax,%eax │ ↓ jne 2b │ mov %rbx,%rax 0 0 5193 │ pop %rbx │ ← retq │2b: mov %eax,%esi │ → callq queued_spin_lock_slowpath │ mov %rbx,%rax │ pop %rbx Press 'h' for help on│key bindings ===================================================================================================== 79273 + 190455 + 198038 + 3045 + 217233 + 32562 + 3421649 + 979174 + 28273 + 5193 = 5154895 Or number of samples: ===================================================================================================== ooSamples: 46 of events 'cycles', 4000 Hz, Event count (approx.): 5154895 _raw_spin_lock_irqsave /proc/kcore Samples │ nop │ push %rbx 0 2 0 │ pushfq 2 0 0 │ pop %rax 2 0 2 │ nop │ mov %rax,%rbx │ cli 1 1 0 │ nop │ xor %eax,%eax │ mov $0x1,%edx │ lock cmpxchg %edx,(%rdi) 17 11 7 │ test %eax,%eax │ ↓ jne 2b │ mov %rbx,%rax 0 0 1 │ pop %rbx │ ← retq │2b: mov %eax,%esi │ → callq queued_spin_lock_slowpath │ mov %rbx,%rax │ pop %rbx Press 'h' for help on key bindings ===================================================================================================== 2 + 2 + 2 + 2 + 1 + 1 + 17 + 11 + 7 + 1 = 46 Suggested-by:Martin Liška <mliska@suse.cz> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: David Ahern <dsahern@gmail.com> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Wang Nan <wangnan0@huawei.com> Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=196935 Link: https://lkml.kernel.org/n/tip-ezccyxld50wtwyt66np6aomo@git.kernel.orgSigned-off-by:
Arnaldo Carvalho de Melo <acme@redhat.com>
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