From: Srividya Desireddy <srividya.dr@samsung.com>
To: Dan Streetman <ddstreet@ieee.org>,
"sjenning@redhat.com" <sjenning@redhat.com>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Cc: Dinakar Reddy Pathireddy <dinakar.p@samsung.com>,
RAJIB BASU <rajib.basu@samsung.com>,
Srikanth Mandalapu <srikanth.m@samsung.com>,
SHARAN ALLUR <sharan.allur@samsung.com>,
JUHUN KIM <juhunkim@samsung.com>,
Srividya Desireddy <srividya.dr@samsung.com>,
"srividya.desireddy@gmail.com" <srividya.desireddy@gmail.com>
Subject: [PATCH] zswap: Update with same-value filled page feature
Date: Wed, 29 Nov 2017 15:34:37 +0000 [thread overview]
Message-ID: <20171129153437epcms5p64b04efa370cc42bb0f9e5677e298704e@epcms5p6> (raw)
In-Reply-To: <CALZtONA1R8HyODqUP8Z-0yxvRAsV=Zo8OD2PQT3HwWWmqE6Hig@mail.gmail.com>
From: Srividya Desireddy <srividya.dr@samsung.com>
Date: Wed, 29 Nov 2017 20:23:15 +0530
Subject: [PATCH] zswap: Update with same-value filled page feature
Updated zswap document with details on same-value filled
pages identification feature.
The usage of zswap.same_filled_pages_enabled module parameter
is explained.
Signed-off-by: Srividya Desireddy <srividya.dr@samsung.com>
---
Documentation/vm/zswap.txt | 22 +++++++++++++++++++++-
1 file changed, 21 insertions(+), 1 deletion(-)
diff --git a/Documentation/vm/zswap.txt b/Documentation/vm/zswap.txt
index 89fff7d..cc015b5 100644
--- a/Documentation/vm/zswap.txt
+++ b/Documentation/vm/zswap.txt
@@ -98,5 +98,25 @@ request is made for a page in an old zpool, it is uncompressed using its
original compressor. Once all pages are removed from an old zpool, the zpool
and its compressor are freed.
+Some of the pages in zswap are same-value filled pages (i.e. contents of the
+page have same value or repetitive pattern). These pages include zero-filled
+pages and they are handled differently. During store operation, a page is
+checked if it is a same-value filled page before compressing it. If true, the
+compressed length of the page is set to zero and the pattern or same-filled
+value is stored.
+
+Same-value filled pages identification feature is enabled by default and can be
+disabled at boot time by setting the "same_filled_pages_enabled" attribute to 0,
+e.g. zswap.same_filled_pages_enabled=0. It can also be enabled and disabled at
+runtime using the sysfs "same_filled_pages_enabled" attribute, e.g.
+
+echo 1 > /sys/module/zswap/parameters/same_filled_pages_enabled
+
+When zswap same-filled page identification is disabled at runtime, it will stop
+checking for the same-value filled pages during store operation. However, the
+existing pages which are marked as same-value filled pages will be loaded or
+invalidated.
+
A debugfs interface is provided for various statistic about pool size, number
-of pages stored, and various counters for the reasons pages are rejected.
+of pages stored, same-value filled pages and various counters for the reasons
+pages are rejected.
--
2.7.4
--
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next prev parent reply other threads:[~2017-11-29 15:34 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
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 ` Srividya Desireddy [this message]
2017-11-29 21:29 ` [PATCH] zswap: Update with same-value filled page feature 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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