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]# -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/