On Mon, 2014-05-26 at 11:04 +0800, Libo Chen wrote:
> hi,
> my box has 16 cpu (E5-2658,8 core, 2 thread per core), i did a test on
> 3.4.24stable, startup 50 same process, every process is sample:
>
> #include <unistd.h>
>
> int main()
> {
> for (;;)
> {
> unsigned int i = 0;
> while (i< 100){
> i++;
> }
> usleep(100);
> }
>
> return 0;
> }
>
> the result is process uses 15% cpu time, perf tool shows 70w migrations in 5
> second.
My 8 socket 64 core DL980 running 256 copies (3.14-rt5) munches ~4%/copy
per top, and does roughly 1 sh*tload migrations, nano-work loop or not.
Turn SD_SHARE_PKG_RESOURCES off at MC (not a noop here), and consumption
drops to ~2%/copy, and migrations ('course) mostly go away.
vogelweide:/abuild/mike/:[0]# perf stat -a -e sched:sched_migrate_task -- sleep
5
Performance counter stats for 'system wide':
3108 sched:sched_migrate_task
5.001367910 seconds time elapsed
(turns SD_SHARE_PKG_RESOURCES back on)
vogelweide:/abuild/mike/:[0]# perf stat -a -e sched:sched_migrate_task -- sleep
5
Performance counter stats for 'system wide':
4182334 sched:sched_migrate_task
5.001365023 seconds time elapsed
vogelweide:/abuild/mike/:[0]#
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