Re: [PATCH v2] perf diff: Report noisy for cycles diff
From: Jiri Olsa
Date: Tue Aug 06 2019 - 04:34:26 EST
On Thu, Jul 25, 2019 at 06:14:32AM +0800, Jin Yao wrote:
> This patch prints the stddev and hist for the cycles diff of
> program block. It can help us to understand if the cycles diff
> is noisy or not.
>
> This patch is inspired by Andi Kleen's patch
> https://lwn.net/Articles/600471/
>
> We create new option '-n or --noisy'.
>
> Example:
>
> perf record -b ./div
> perf record -b ./div
> perf diff -c cycles
>
> # Event 'cycles'
> #
> # Baseline [Program Block Range] Cycles Diff Shared Object Symbol
> # ........ ...................................................................... ................. ................................
> #
> 46.42% [div.c:40 -> div.c:40] 0 div [.] main
> 46.42% [div.c:42 -> div.c:44] 0 div [.] main
> 46.42% [div.c:42 -> div.c:39] 0 div [.] main
> 20.72% [random_r.c:357 -> random_r.c:394] -2 libc-2.27.so [.] __random_r
> 20.72% [random_r.c:357 -> random_r.c:380] -1 libc-2.27.so [.] __random_r
> 20.72% [random_r.c:388 -> random_r.c:388] 0 libc-2.27.so [.] __random_r
> 20.72% [random_r.c:388 -> random_r.c:391] 0 libc-2.27.so [.] __random_r
> 17.58% [random.c:288 -> random.c:291] 0 libc-2.27.so [.] __random
> 17.58% [random.c:291 -> random.c:291] 0 libc-2.27.so [.] __random
> 17.58% [random.c:293 -> random.c:293] 0 libc-2.27.so [.] __random
> 17.58% [random.c:295 -> random.c:295] 0 libc-2.27.so [.] __random
> 17.58% [random.c:295 -> random.c:295] 0 libc-2.27.so [.] __random
> 17.58% [random.c:298 -> random.c:298] 0 libc-2.27.so [.] __random
> 8.33% [div.c:22 -> div.c:25] 0 div [.] compute_flag
> 8.33% [div.c:27 -> div.c:28] 0 div [.] compute_flag
> 4.80% [rand.c:26 -> rand.c:27] 0 libc-2.27.so [.] rand
> 4.80% [rand.c:28 -> rand.c:28] 0 libc-2.27.so [.] rand
> 2.14% [rand@plt+0 -> rand@plt+0] 0 div [.] rand@plt
>
> When we enable the option '-n' or '--noisy', the output is
>
> perf diff -c cycles -n
>
> # Event 'cycles'
> #
> # Baseline [Program Block Range]/Cycles Diff/stddev/Hist Shared Object Symbol
> # ........ ................................................................................ ................. ................................
> #
> 46.42% [div.c:40 -> div.c:40] 0 Â 40.2% ââââââââ div [.] main
> 46.42% [div.c:42 -> div.c:44] 0 Â100.0% ââââââââ div [.] main
> 46.42% [div.c:42 -> div.c:39] 0 Â 15.3% ââââââââ div [.] main
> 20.72% [random_r.c:357 -> random_r.c:394] -2 Â 20.1% ââââââââ libc-2.27.so [.] __random_r
> 20.72% [random_r.c:357 -> random_r.c:380] -1 Â 20.9% ââââââââ libc-2.27.so [.] __random_r
> 20.72% [random_r.c:388 -> random_r.c:388] 0 Â 0.0% libc-2.27.so [.] __random_r
> 20.72% [random_r.c:388 -> random_r.c:391] 0 Â 88.0% ââââââââ libc-2.27.so [.] __random_r
> 17.58% [random.c:288 -> random.c:291] 0 Â 29.3% ââââââââ libc-2.27.so [.] __random
> 17.58% [random.c:291 -> random.c:291] 0 Â 29.3% ââââââââ libc-2.27.so [.] __random
> 17.58% [random.c:293 -> random.c:293] 0 Â 29.3% ââââââââ libc-2.27.so [.] __random
> 17.58% [random.c:295 -> random.c:295] 0 Â 0.0% libc-2.27.so [.] __random
> 17.58% [random.c:295 -> random.c:295] 0 Â 0.0% libc-2.27.so [.] __random
> 17.58% [random.c:298 -> random.c:298] 0 Â 0.0% libc-2.27.so [.] __random
> 8.33% [div.c:22 -> div.c:25] 0 Â 29.3% ââââââââ div [.] compute_flag
> 8.33% [div.c:27 -> div.c:28] 0 Â 48.8% ââââââââ div [.] compute_flag
> 4.80% [rand.c:26 -> rand.c:27] 0 Â 29.3% ââââââââ libc-2.27.so [.] rand
> 4.80% [rand.c:28 -> rand.c:28] 0 Â 0.0% libc-2.27.so [.] rand
> 2.14% [rand@plt+0 -> rand@plt+0] 0 Â 0.0% div [.] rand@plt
I'm getting some unaligned lines:
# Event 'cycles'
#
# Baseline [Program Block Range]/Cycles Diff/stddev/Hist Shared Object Symbol
# ........ ................................................................................ ................... ..............................................
#
11.87% [do_syscall_64+0 -> do_syscall_64+30] -22 Â 91.8% ââ [kernel.kallsyms] [k] do_syscall_64
11.87% [do_syscall_64+0 -> do_syscall_64+47] -3 Â 84.9% ââââââââ [kernel.kallsyms] [k] do_syscall_64
11.87% [do_syscall_64+91 -> do_syscall_64+118] -1 Â 33.5% ââââââââ [kernel.kallsyms] [k] do_syscall_64
11.87% [do_syscall_64+0 -> do_syscall_64+286] 0 Â100.0% ââââââââ [kernel.kallsyms] [k] do_syscall_64
11.87% [do_syscall_64+0 -> do_syscall_64+332] 0 Â 0.0% [kernel.kallsyms] [k] do_syscall_64
11.87% [do_syscall_64+53 -> do_syscall_64+86] 0 Â 0.0% [kernel.kallsyms] [k] do_syscall_64
11.87% [do_syscall_64+124 -> do_syscall_64+148] 0 Â 26.3% ââââââââ [kernel.kallsyms] [k] do_syscall_64
11.87% [do_syscall_64+181 -> do_syscall_64+219] 0 Â 38.9% ââââââââ [kernel.kallsyms] [k] do_syscall_64
11.87% [do_syscall_64+278 -> do_syscall_64+281] 0 Â 0.0% [kernel.kallsyms] [k] do_syscall_64
11.87% [do_syscall_64+291 -> do_syscall_64+294] 0 Â100.0% ââââââââ [kernel.kallsyms] [k] do_syscall_64
6.76% [psi_task_change+421 -> psi_task_change+440] -5 Â 45.6% ââââââââ [kernel.kallsyms] [k] psi_task_change
6.76% [psi_task_change+0 -> psi_task_change+60] -3 Â 47.9% ââââââââ [kernel.kallsyms] [k] psi_task_change
6.76% [psi_task_change+126 -> psi_task_change+225] -2 Â 22.8% ââââââââ [kernel.kallsyms] [k] psi_task_change
6.76% [psi_task_change+126 -> psi_task_change+172] -1 Â 48.8% ââââââââ [kernel.kallsyms] [k] psi_task_change
6.76% [psi_task_change+476 -> psi_task_change+488] -1 Â 39.9% ââââââââ [kernel.kallsyms] [k] psi_task_change
6.76% [psi_task_change+80 -> psi_task_change+118] 0 Â 50.0% ââââââââ [kernel.kallsyms] [k] psi_task_change
6.76% [psi_task_change+80 -> psi_task_change+129] 0 Â 48.9% ââââââââ [kernel.kallsyms] [k] psi_task_change
6.76% [psi_task_change+126 -> psi_task_change+142] 0 Â 0.0% [kernel.kallsyms] [k] psi_task_change
6.76% [psi_task_change+230 -> psi_task_change+252] 0 Â 0.0% [kernel.kallsyms] [k] psi_task_change
6.76% [psi_task_change+230 -> psi_task_change+265] 0 Â 0.0% [kernel.kallsyms] [k] psi_task_change
6.76% [psi_task_change+254 -> psi_task_change+324] 0 Â100.0% ââââââââ [kernel.kallsyms] [k] psi_task_change
6.76% [psi_task_change+298 -> psi_task_change+307] 0 Â 0.0% [kernel.kallsyms] [k] psi_task_change
6.76% [psi_task_change+309 -> psi_task_change+332] 0 Â 37.8% ââââââââ [kernel.kallsyms] [k] psi_task_change
6.76% [psi_task_change+326 -> psi_task_change+370] 0 Â 79.5% ââââââââ [kernel.kallsyms] [k] psi_task_change
6.76% [psi_task_change+341 -> psi_task_change+348] 0 Â 0.0% [kernel.kallsyms] [k] psi_task_change
6.76% [psi_task_change+446 -> psi_task_change+456] 0 Â 0.0% [kernel.kallsyms] [k] psi_task_change
6.76% [psi_task_change+461 -> psi_task_change+475] 0 Â 0.0% [kernel.kallsyms] [k] psi_task_change
6.76% [psi_task_change+493 -> psi_task_change+497] 0 Â 77.8% ââââââââ [kernel.kallsyms] [k] psi_task_change
5.27% [syscall_return_via_sysret+0 -> syscall_return_via_sysret+81] -21 Â 28.1% ââââââââ [kernel.kallsyms] [k] syscall_return_via_sysret
5.27% [syscall_return_via_sysret+0 -> syscall_return_via_sysret+66] 0 Â 48.7% ââââââââ [kernel.kallsyms] [k] syscall_return_via_sysret
5.27% [syscall_return_via_sysret+83 -> syscall_return_via_sysret+114] 0 Â 12.8% ââââââââ [kernel.kallsyms] [k] syscall_return_via_sysret
4.22% [native_write_msr+0 -> native_write_msr+11] 0 Â 24.6% ââââââââ [kernel.kallsyms] [k] native_write_msr
2.84% [enqueue_task_fair+257 -> enqueue_task_fair+281] -168 Â 94.5% ââ [kernel.kallsyms] [k] enqueue_task_fair
2.84% [enqueue_task_fair+904 -> enqueue_task_fair+916] -122 Â 0.0% [kernel.kallsyms] [k] enqueue_task_fair
2.84% [enqueue_task_fair+93 -> enqueue_task_fair+98] 27 Â 8.6% ââ [kernel.kallsyms] [k] enqueue_task_fair
2.84% [enqueue_task_fair+286 -> enqueue_task_fair+289] 5 Â 85.5% âââ [kernel.kallsyms] [k] enqueue_task_fair
2.84% [enqueue_task_fair+0 -> enqueue_task_fair+120] -3 Â 19.5% ââââââââ [kernel.kallsyms] [k] enqueue_task_fair
thanks,
jirka