Re: [PATCH 3/5] oom: create oom autogroup

[Minchan Kim <minchan.kim@xxxxxxxxx>]

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.
>
> Â------------------------------------------------------------------------------
> ÂTask         Â|  Runtime ms Â| Average delay ms | Maximum delay ms |
> Â------------------------------------------------------------------------------
> Âpython:1754 Â Â Â Â Â | Â Â Â0.197 ms | avg: 1731.727 ms | max: 3433.805 ms |
> Âpython:1843 Â Â Â Â Â | Â Â Â0.489 ms | avg: 1707.433 ms | max: 3622.955 ms |
> Âpython:1715 Â Â Â Â Â | Â Â Â0.220 ms | avg: 1707.125 ms | max: 3623.246 ms |
> Âpython:1818 Â Â Â Â Â | Â Â Â2.127 ms | avg: 1527.331 ms | max: 3622.553 ms |
> Â...
> Â...
>
> 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.

Could it make unnecessary killing of other tasks?
I am not sure. Just out of curiosity.

Thanks for nice work, Kosaki.
-- 
Kind regards,
Minchan Kim

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