Re: [RFC][-mm][PATCH 5/6] oom-killer: check last total_vmexpansion

From: David Rientjes
Date: Tue Nov 03 2009 - 15:29:52 EST

On Mon, 2 Nov 2009, KAMEZAWA Hiroyuki wrote:

> From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
> At considering oom-kill algorithm, we can't avoid to take runtime
> into account. But this can adds too big bonus to slow-memory-leaker.
> For adding penalty to slow-memory-leaker, we record jiffies of
> the last mm->hiwater_vm expansion. That catches processes which leak
> memory periodically.

No, it doesn't, it simply measures the last time the hiwater mark was
increased. That could have increased by a single page in the last tick
with no increase in memory consumption over the past year and then its
unfairly biased against for quiet_time in the new oom kill heuristic
(patch 6). Using this as part of the badness scoring is ill conceived
because it doesn't necessarily indicate a memory leaking task, just one
that has recently allocated memory.
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