From: Dave Chinner <david@fromorbit.com>
To: "Nag Avadhanam (nag)" <nag@cisco.com>
Cc: Theodore Ts'o <tytso@mit.edu>,
"Daniel Walker (danielwa)" <danielwa@cisco.com>,
Alexander Viro <viro@zeniv.linux.org.uk>,
"Khalid Mughal (khalidm)" <khalidm@cisco.com>,
"xe-kernel@external.cisco.com" <xe-kernel@external.cisco.com>,
"dave.hansen@intel.com" <dave.hansen@intel.com>,
"hannes@cmpxchg.org" <hannes@cmpxchg.org>,
"riel@redhat.com" <riel@redhat.com>,
Jonathan Corbet <corbet@lwn.net>,
"linux-doc@vger.kernel.org" <linux-doc@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
"linux-mm@kvack.org" <linux-mm@kvack.org>
Subject: Re: [PATCH] kernel: fs: drop_caches: add dds drop_caches_count
Date: Tue, 16 Feb 2016 16:38:28 +1100 [thread overview]
Message-ID: <20160216053827.GX19486@dastard> (raw)
In-Reply-To: <D2E7B337.D5404%nag@cisco.com>
On Tue, Feb 16, 2016 at 02:58:04AM +0000, Nag Avadhanam (nag) wrote:
> Its the calculation of the # of bytes of non-reclaimable file system cache
> pages that has been troubling us. We do not want to count inactive file
> pages (of programs/binaries) that were once mapped by any process in the
> system as reclaimable because that might lead to thrashing under memory
> pressure (we want to alert admins before system starts dropping text
> pages).
The code presented does not match your requirements. It only counts
pages that are currently mapped into ptes. hence it will tell you
that once-used and now unmapped binary pages are reclaimable, and
drop caches will reclaim them. hence they'll need to be fetched from
disk again if they are faulted in again after a drop_caches run.
Cheers,
Dave.
--
Dave Chinner
david@fromorbit.com
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next prev parent reply other threads:[~2016-02-16 5:38 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-12 20:14 [PATCH] kernel: fs: drop_caches: add dds drop_caches_count Daniel Walker
2016-02-14 21:18 ` Dave Chinner
2016-02-15 18:19 ` Daniel Walker
2016-02-15 23:05 ` Dave Chinner
2016-02-15 23:52 ` Daniel Walker
2016-02-16 0:45 ` Theodore Ts'o
2016-02-16 2:58 ` Nag Avadhanam (nag)
2016-02-16 5:38 ` Dave Chinner [this message]
2016-02-16 7:14 ` Nag Avadhanam
2016-02-16 8:35 ` Dave Chinner
2016-02-16 8:43 ` Vladimir Davydov
2016-02-16 18:37 ` Nag Avadhanam
2016-02-16 5:28 ` Dave Chinner
2016-02-16 5:57 ` Nag Avadhanam
2016-02-16 8:22 ` Dave Chinner
2016-02-16 16:12 ` Rik van Riel
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