From: Andi Kleen <ak@linux.intel.com>
To: Srividya Desireddy <srividya.dr@samsung.com>
Cc: "sjenning@redhat.com" <sjenning@redhat.com>,
"ddstreet@ieee.org" <ddstreet@ieee.org>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"penberg@kernel.org" <penberg@kernel.org>,
Dinakar Reddy Pathireddy <dinakar.p@samsung.com>,
SHARAN ALLUR <sharan.allur@samsung.com>,
RAJIB BASU <rajib.basu@samsung.com>,
JUHUN KIM <juhunkim@samsung.com>,
"srividya.desireddy@gmail.com" <srividya.desireddy@gmail.com>
Subject: Re: [PATCH] zswap: Same-filled pages handling
Date: Wed, 18 Oct 2017 13:43:10 -0700 [thread overview]
Message-ID: <8760bci3vl.fsf@linux.intel.com> (raw)
In-Reply-To: <20171018104832epcms5p1b2232e2236258de3d03d1344dde9fce0@epcms5p1> (Srividya Desireddy's message of "Wed, 18 Oct 2017 10:48:32 +0000")
Srividya Desireddy <srividya.dr@samsung.com> writes:
>
> On a ARM Quad Core 32-bit device with 1.5GB RAM by launching and
> relaunching different applications, out of ~64000 pages stored in
> zswap, ~11000 pages were same-value filled pages (including zero-filled
> pages) and ~9000 pages were zero-filled pages.
What are the values for the non zero cases?
> +static int zswap_is_page_same_filled(void *ptr, unsigned long *value)
> +{
> + unsigned int pos;
> + unsigned long *page;
> +
> + page = (unsigned long *)ptr;
> + for (pos = 1; pos < PAGE_SIZE / sizeof(*page); pos++) {
> + if (page[pos] != page[0])
> + return 0;
> + }
So on 32bit it checks for 32bit repeating values and on 64bit
for 64bit repeating values. Does that make sense?
Did you test the patch on a 64bit system?
Overall I would expect this extra pass to be fairly expensive. It may
be better to add some special check to the compressor, and let
it abort if it sees a string of same values, and only do the check
then.
-Andi
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next prev parent reply other threads:[~2017-10-18 20:43 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CGME20171018104832epcms5p1b2232e2236258de3d03d1344dde9fce0@epcms5p1>
2017-10-18 10:48 ` [PATCH] zswap: Same-filled pages handling Srividya Desireddy
2017-10-18 12:34 ` Matthew Wilcox
2017-10-18 13:33 ` Timofey Titovets
2017-10-18 14:11 ` Matthew Wilcox
2017-10-18 20:43 ` Andi Kleen [this message]
2017-10-19 1:10 ` Matthew Wilcox
2017-10-19 4:30 ` Andi Kleen
2017-10-19 13:24 ` Matthew Wilcox
2017-10-18 21:31 ` Timofey Titovets
2017-10-19 1:08 ` Matthew Wilcox
[not found] ` <CGME20171018104832epcms5p1b2232e2236258de3d03d1344dde9fce0@epcms5p3>
2017-11-02 15:08 ` Srividya Desireddy
2017-11-17 22:10 ` Dan Streetman
2017-11-17 22:07 ` Dan Streetman
2017-11-17 21:27 ` Dan Streetman
2017-11-20 23:46 ` Andrew Morton
2017-11-28 11:35 ` Dan Streetman
[not found] ` <CGME20171018104832epcms5p1b2232e2236258de3d03d1344dde9fce0@epcms5p6>
2017-11-29 15:34 ` [PATCH] zswap: Update with same-value filled page feature Srividya Desireddy
2017-11-29 21:29 ` Dan Streetman
2017-12-06 11:48 ` [PATCH v2] " Srividya Desireddy
2017-12-06 15:20 ` Dan Streetman
[not found] ` <CGME20171018104832epcms5p1b2232e2236258de3d03d1344dde9fce0@epcms5p4>
2017-11-21 14:18 ` [PATCH v2] zswap: Same-filled pages handling Srividya Desireddy
2017-10-18 14:43 ` [PATCH] " Srividya Desireddy
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