Re: [PATCH] perf diff: Report noisy for cycles diff
On 7/16/2019 4:51 PM, Jiri Olsa wrote:
On Fri, Jul 12, 2019 at 03:53:55PM +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.
I'm getting compile error:
CC builtin-diff.o
builtin-diff.c: In function ‘compute_cycles_diff’:
builtin-diff.c:712:10: error: taking the absolute value of unsigned type ‘u64’
{aka ‘long unsigned int’} has no effect [-Werror=absolute-value]
712 | labs(pair->block_info->cycles_spark[i] -
| ^~~~
cc1: all warnings being treated as errors
mv: cannot stat './.builtin-diff.o.tmp': No such file or directory
Oh, sorry about that. My gcc (gcc version 7.4.0 (Ubuntu
7.4.0-1ubuntu1~18.04.1)) didn't report this error. :(
u64 - u64 is u64. I should define it as s64.
Thanks for reminding me.
Thanks
Jin Yao
jirka
Re: [PATCH] perf diff: Report noisy for cycles diff
On Fri, Jul 12, 2019 at 03:53:55PM +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.
I'm getting compile error:
CC builtin-diff.o
builtin-diff.c: In function ‘compute_cycles_diff’:
builtin-diff.c:712:10: error: taking the absolute value of unsigned type ‘u64’
{aka ‘long unsigned int’} has no effect [-Werror=absolute-value]
712 | labs(pair->block_info->cycles_spark[i] -
| ^~~~
cc1: all warnings being treated as errors
mv: cannot stat './.builtin-diff.o.tmp': No such file or directory
jirka
[PATCH] perf diff: Report noisy for cycles diff
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', 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 ± 40.2% ▂███▁▂▁▁ div[.] main 46.42%[div.c:42 -> div.c:44]0 ±100.0% █▁▁▁ div[.] main 46.42%[div.c:42 -> div.c:39]0 ± 15.3% ▃▃▂▆▃▂█▁ div[.] main 20.72%[random_r.c:357 -> random_r.c:394] -2 ± 20.1% ▁▄▄▅▂▅█▁ libc-2.27.so [.] __random_r 20.72%[random_r.c:357 -> random_r.c:380] -1 ± 20.9% ▁▆▇▁█▅▇█ libc-2.27.so [.] __random_r 20.72%[random_r.c:388 -> random_r.c:388]0 ± 0.0%libc-2.27.so [.] __random_r 20.72%[random_r.c:388 -> random_r.c:391]0 ± 88.0% ▁▁▁█ libc-2.27.so [.] __random_r 17.58%[random.c:288 -> random.c:291]0 ± 29.3% ▁▁█▁ libc-2.27.so [.] __random 17.58%[random.c:291 -> random.c:291]0 ± 29.3% ▁▁▁█ libc-2.27.so [.] __random 17.58%[random.c:293 -> random.c:293]0 ± 29.3% ▁▁▁█ libc-2.27.so [.] __random 17.58%[random.c:295 -> random.c:295]0 ± 0.0%libc-2.27.so [.] __random 17.58%[random.c:295 -> random.c:295]0 ± 0.0%libc-2.27.so [.] __random 17.58%[random.c:298 -> random.c:298]0 ± 0.0%libc-2.27.so [.] __random 8.33%[div.c:22 -> div.c:25]0 ± 29.3% ▁▁█▁ div[.] compute_flag 8.33%[div.c:27 -> div.c:28]0 ± 48.8% ▁██▁▁▁█▁ div
