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Date: Wed, 20 Nov 2013 19:36:00 -0800 (PST) From: David Rientjes <rientjes@...gle.com> To: Luigi Semenzato <semenzato@...gle.com> cc: Michal Hocko <mhocko@...e.cz>, linux-mm@...ck.org, Greg Thelen <gthelen@...gle.com>, Glauber Costa <glommer@...il.com>, Mel Gorman <mgorman@...e.de>, Andrew Morton <akpm@...ux-foundation.org>, Johannes Weiner <hannes@...xchg.org>, KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>, Rik van Riel <riel@...hat.com>, Joern Engel <joern@...fs.org>, Hugh Dickins <hughd@...gle.com>, LKML <linux-kernel@...r.kernel.org> Subject: Re: user defined OOM policies On Wed, 20 Nov 2013, Luigi Semenzato wrote: > Chrome OS uses a custom low-memory notification to minimize OOM kills. > When the notifier triggers, the Chrome browser tries to free memory, > including by shutting down processes, before the full OOM occurs. But > OOM kills cannot always be avoided, depending on the speed of > allocation and how much CPU the freeing tasks are able to use > (certainly they could be given higher priority, but it get complex). > > We may end up using memcg so we can use the cgroup > memory.pressure_level file instead of our own notifier, but we have no > need for finer control over OOM kills beyond the very useful kill > priority. One process at a time is good enough for us. > Even with your own custom low-memory notifier or memory.pressure_level, it's still possible that all memory is depleted and you run into an oom kill before your userspace had a chance to wakeup and prevent it. I think what you'll want is either your custom notifier of memory.pressure_level to do pre-oom freeing but fallback to a userspace oom handler that prevents kernel oom kills until it ensures userspace did everything it could to free unneeded memory, do any necessary logging, etc, and do so over a grace period of memory.oom_delay_millisecs before the kernel eventually steps in and kills. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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