From: Dave Hansen <dave.hansen@intel.com>
To: "Khalid Mughal (khalidm)" <khalidm@cisco.com>,
Rik van Riel <riel@redhat.com>,
"Daniel Walker (danielwa)" <danielwa@cisco.com>,
Johannes Weiner <hannes@cmpxchg.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>,
Michal Hocko <mhocko@suse.com>,
Andrew Morton <akpm@linux-foundation.org>,
"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
"xe-kernel@external.cisco.com" <xe-kernel@external.cisco.com>
Subject: Re: computing drop-able caches
Date: Fri, 12 Feb 2016 13:46:54 -0800 [thread overview]
Message-ID: <56BE52CE.5070403@intel.com> (raw)
In-Reply-To: <D2E35753.2BB9D%khalidm@cisco.com>
On 02/12/2016 10:01 AM, Khalid Mughal (khalidm) wrote:
> If you look at the attached pdf, you will notice that OOM messages start
> to appear when memAvailable is showing 253MB (259228 KB) Free, memFree is
> 13.5MB (14008 KB) Free, and dropcache based calculation �Available memory�
> is showing 21MB (21720 KB) Free.
>
> So, it appears that memAvailable is not as accurate, especially if data is
> used to warn user about system running low on memory.
Yep, that's true.
But, MemAvailable is calculated from some very cheap counters. The
"dropcache-based-calculation" requires iterating over every 4k page
cache page in the system.
Do you have some ideas for doing cheap(er) MemAvailable calculations?
We track dirty and writebackw with counters, so we should theoretically
be able to pull those out of MemAvailable fairly cheaply.
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next prev parent reply other threads:[~2016-02-12 21:46 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-01-28 23:42 computing drop-able caches Daniel Walker
2016-01-28 23:58 ` Johannes Weiner
2016-01-29 1:03 ` Daniel Walker
2016-01-29 1:29 ` Daniel Walker
2016-01-29 1:55 ` Johannes Weiner
2016-01-29 21:21 ` Daniel Walker
2016-01-29 22:33 ` Johannes Weiner
2016-01-29 22:41 ` Rik van Riel
2016-02-08 20:57 ` Khalid Mughal (khalidm)
2016-02-10 18:04 ` Daniel Walker
2016-02-10 18:13 ` Dave Hansen
2016-02-10 19:11 ` Daniel Walker
2016-02-11 22:11 ` Rik van Riel
2016-02-12 18:01 ` Khalid Mughal (khalidm)
2016-02-12 21:46 ` Dave Hansen [this message]
2016-02-12 22:15 ` Johannes Weiner
2016-02-12 18:06 ` Dave Hansen
2016-02-12 18:15 ` Daniel Walker
2016-02-12 18:18 ` Dave Hansen
2016-02-12 18:25 ` Daniel Walker
2016-02-12 20:15 ` Daniel Walker
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