linux-kernel - Re: Sudden and massive page cache eviction

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Message-ID: <AANLkTik2Fn-ynUap2fPcRxRdKA=5ZRYG0LJTmqf80y+q@mail.gmail.com>
Date:	Tue, 23 Nov 2010 10:44:42 +0100
From:	Peter Schüller <scode@...tify.com>
To:	Dave Hansen <dave@...ux.vnet.ibm.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org,
	Mattias de Zalenski <zalenski@...tify.com>,
	linux-mm@...ck.org
Subject: Re: Sudden and massive page cache eviction

> You don't have anybody messing with /proc/sys/vm/drop_caches, do you?

Highly unlikely given that (1) evictions, while often very
significant, are usually not *complete* (although the first graph
example I provided had a more or less complete eviction) and (2) the
evictions are not obviously periodic indicating some kind of cron job,
and (3) we see the evictions happening across a wide variety of
machines.

So yes, I feel confident that we are not accidentally doing that.

(FWIW though, drop_caches is great. I only recently found out about
it, and it's really useful when benchmarking.)

-- 
/ Peter Schuller aka scode
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