From: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
To: Seth Jennings <sjenning@redhat.com>
Cc: srividya.dr@samsung.com, "ddstreet@ieee.org" <ddstreet@ieee.org>,
"penberg@kernel.org" <penberg@kernel.org>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Dinakar Reddy Pathireddy <dinakar.p@samsung.com>,
SHARAN ALLUR <sharan.allur@samsung.com>,
SUNEEL KUMAR SURIMANI <suneel@samsung.com>,
JUHUN KIM <juhunkim@samsung.com>,
"srividya.desireddy@gmail.com" <srividya.desireddy@gmail.com>
Subject: Re: [PATCH v2] zswap: Zero-filled pages handling
Date: Thu, 6 Jul 2017 14:19:59 +0900 [thread overview]
Message-ID: <20170706051959.GD7195@jagdpanzerIV.localdomain> (raw)
In-Reply-To: <CAC8qmcBa3ZBpw12AjbZ8bWuK5DW=wiXcURzomqXZXLrQhUWDhg@mail.gmail.com>
On (07/02/17 20:28), Seth Jennings wrote:
> On Sun, Jul 2, 2017 at 9:19 AM, Srividya Desireddy
> > Zswap is a cache which compresses the pages that are being swapped out
> > and stores them into a dynamically allocated RAM-based memory pool.
> > Experiments have shown that around 10-20% of pages stored in zswap
> > are zero-filled pages (i.e. contents of the page are all zeros), but
> > these pages are handled as normal pages by compressing and allocating
> > memory in the pool.
>
> I am somewhat surprised that this many anon pages are zero filled.
>
> If this is true, then maybe we should consider solving this at the
> swap level in general, as we can de-dup zero pages in all swap
> devices, not just zswap.
>
> That being said, this is a fair small change and I don't see anything
> objectionable. However, I do think the better solution would be to do
> this at a higher level.
zero-filled pages are just 1 case. in general, it's better
to handle pages that are memset-ed with the same value (e.g.
memset(page, 0x01, page_size)). which includes, but not
limited to, 0x00. zram does it.
-ss
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next prev parent reply other threads:[~2017-07-06 5:19 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CGME20170702141959epcms5p32119c772b960e942da3a92e5a79d8c41@epcms5p3>
2017-07-02 14:19 ` [PATCH v2] zswap: Zero-filled pages handling Srividya Desireddy
2017-07-03 1:28 ` Seth Jennings
2017-07-06 5:19 ` Sergey Senozhatsky [this message]
[not found] ` <CGME20170702141959epcms5p32119c772b960e942da3a92e5a79d8c41@epcms5p5>
2017-07-06 9:29 ` Srividya Desireddy
2017-07-06 10:02 ` Dan Streetman
[not found] <CGME20170816172008epcms5p24e951e01951f055559210af10edf2250@epcms5p2>
2017-08-16 17:20 ` Srividya Desireddy
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