From: Johannes Weiner <hannes@cmpxchg.org>
To: Daniel Walker <danielwa@cisco.com>
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-kernel@vger.kernel.org,
linux-mm@kvack.org, "Khalid Mughal (khalidm)" <khalidm@cisco.com>,
"xe-kernel@external.cisco.com" <xe-kernel@external.cisco.com>,
Rik van Riel <riel@redhat.com>
Subject: Re: computing drop-able caches
Date: Thu, 28 Jan 2016 20:55:34 -0500 [thread overview]
Message-ID: <20160129015534.GA6401@cmpxchg.org> (raw)
In-Reply-To: <56AAC085.9060509@cisco.com>
On Thu, Jan 28, 2016 at 05:29:41PM -0800, Daniel Walker wrote:
> On 01/28/2016 05:03 PM, Daniel Walker wrote:
> [regarding MemAvaiable]
>
> This new metric purportedly helps usrespace assess available memory. But,
> its again based on heuristic, it takes 1/2 of page cache as reclaimable..
No, it takes the smaller value of cache/2 and the low watermark, which
is a fraction of memory. Actually, that does look a little weird. Rik?
We don't age cache without memory pressure, you don't know how much is
used until you start taking some away. Heuristics is all we can offer.
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WARNING: multiple messages have this Message-ID (diff)
From: Johannes Weiner <hannes@cmpxchg.org>
To: Daniel Walker <danielwa@cisco.com>
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-kernel@vger.kernel.org,
linux-mm@kvack.org, "Khalid Mughal (khalidm)" <khalidm@cisco.com>,
"xe-kernel@external.cisco.com" <xe-kernel@external.cisco.com>,
Rik van Riel <riel@redhat.com>
Subject: Re: computing drop-able caches
Date: Thu, 28 Jan 2016 20:55:34 -0500 [thread overview]
Message-ID: <20160129015534.GA6401@cmpxchg.org> (raw)
In-Reply-To: <56AAC085.9060509@cisco.com>
On Thu, Jan 28, 2016 at 05:29:41PM -0800, Daniel Walker wrote:
> On 01/28/2016 05:03 PM, Daniel Walker wrote:
> [regarding MemAvaiable]
>
> This new metric purportedly helps usrespace assess available memory. But,
> its again based on heuristic, it takes 1/2 of page cache as reclaimable..
No, it takes the smaller value of cache/2 and the low watermark, which
is a fraction of memory. Actually, that does look a little weird. Rik?
We don't age cache without memory pressure, you don't know how much is
used until you start taking some away. Heuristics is all we can offer.
next prev parent reply other threads:[~2016-01-29 1:55 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-01-28 23:42 computing drop-able caches Daniel Walker
2016-01-28 23:42 ` Daniel Walker
2016-01-28 23:58 ` Johannes Weiner
2016-01-28 23:58 ` Johannes Weiner
2016-01-29 1:03 ` Daniel Walker
2016-01-29 1:03 ` Daniel Walker
2016-01-29 1:29 ` Daniel Walker
2016-01-29 1:55 ` Johannes Weiner [this message]
2016-01-29 1:55 ` Johannes Weiner
2016-01-29 21:21 ` Daniel Walker
2016-01-29 21:21 ` Daniel Walker
2016-01-29 22:33 ` Johannes Weiner
2016-01-29 22:33 ` Johannes Weiner
2016-01-29 22:41 ` Rik van Riel
2016-01-29 22:41 ` Rik van Riel
2016-02-08 20:57 ` Khalid Mughal (khalidm)
2016-02-08 20:57 ` Khalid Mughal (khalidm)
2016-02-10 18:04 ` Daniel Walker
2016-02-10 18:04 ` Daniel Walker
2016-02-10 18:13 ` Dave Hansen
2016-02-10 18:13 ` Dave Hansen
2016-02-10 19:11 ` Daniel Walker
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
2016-02-12 21:46 ` Dave Hansen
2016-02-12 21:46 ` Dave Hansen
2016-02-12 22:15 ` Johannes Weiner
2016-02-12 22:15 ` Johannes Weiner
2016-02-12 22:15 ` Johannes Weiner
2016-02-12 18:06 ` Dave Hansen
2016-02-12 18:06 ` Dave Hansen
2016-02-12 18:15 ` Daniel Walker
2016-02-12 18:15 ` Daniel Walker
2016-02-12 18:18 ` Dave Hansen
2016-02-12 18:18 ` Dave Hansen
2016-02-12 18:25 ` Daniel Walker
2016-02-12 18:25 ` Daniel Walker
2016-02-12 20:15 ` Daniel Walker
2016-02-12 20:15 ` Daniel Walker
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