On Wed, 2011-03-23 at 10:27 +0900, KOSAKI Motohiro wrote: > > On Tue, Mar 22, 2011 at 8:08 PM, KOSAKI Motohiro > > <kosaki.motohiro@xxxxxxxxxxxxxx> wrote: > > > When plenty processes (eg fork bomb) are running, the TIF_MEMDIE task > > > never exit, at least, human feel it's never. therefore kernel become > > > hang-up. > > > > > > "perf sched" tell us a hint. > > > > > > ------------------------------------------------------------------------------ > > > Task | Runtime ms | Average delay ms | Maximum delay ms | > > > ------------------------------------------------------------------------------ > > > python:1754 | 0.197 ms | avg: 1731.727 ms | max: 3433.805 ms | > > > python:1843 | 0.489 ms | avg: 1707.433 ms | max: 3622.955 ms | > > > python:1715 | 0.220 ms | avg: 1707.125 ms | max: 3623.246 ms | > > > python:1818 | 2.127 ms | avg: 1527.331 ms | max: 3622.553 ms | > > > ... > > > ... > > > > > > Processes flood makes crazy scheduler delay. and then the victim process > > > can't run enough. Grr. Should we do? > > > > > > Fortunately, we already have anti process flood framework, autogroup! > > > This patch reuse this framework and avoid kernel live lock. > > > > That's cool idea but I have a concern. > > > > You remove boosting priority in [2/5] and move victim tasks into autogroup. > > If I understand autogroup right, victim process and threads in the > > process take less schedule chance than now. > > Right. Icky cpu-cgroup rt-runtime default enforce me to seek another solution. I was going to mention rt, and there's s/fork/clone as well. > Today, I got private mail from Luis and he seems to have another improvement > idea. so, I might drop this patch if his one works fine. Perhaps if TIF_MEMDIE threads needs special treatment, preemption tests could take that into account? (though I don't like touching fast path for oddball cases) -Mike -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>