lists.openwall.net   lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  linux-cve-announce  PHC 
Open Source and information security mailing list archives
 
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <20171129153437epcms5p64b04efa370cc42bb0f9e5677e298704e@epcms5p6>
Date:   Wed, 29 Nov 2017 15:34:37 +0000
From:   Srividya Desireddy <srividya.dr@...sung.com>
To:     Dan Streetman <ddstreet@...e.org>,
        "sjenning@...hat.com" <sjenning@...hat.com>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC:     Dinakar Reddy Pathireddy <dinakar.p@...sung.com>,
        RAJIB BASU <rajib.basu@...sung.com>,
        Srikanth Mandalapu <srikanth.m@...sung.com>,
        SHARAN ALLUR <sharan.allur@...sung.com>,
        JUHUN KIM <juhunkim@...sung.com>,
        Srividya Desireddy <srividya.dr@...sung.com>,
        "srividya.desireddy@...il.com" <srividya.desireddy@...il.com>
Subject: [PATCH] zswap: Update with same-value filled page feature

From: Srividya Desireddy <srividya.dr@...sung.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@...sung.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

Powered by blists - more mailing lists

Powered by Openwall GNU/*/Linux Powered by OpenVZ