The patch titled
Subject: Documentation/vm/zswap.txt: update with same-value filled page feature
has been added to the -mm tree. Its filename is
zswap-update-with-same-value-filled-page-feature.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/zswap-update-with-same-value-filled-page-feature.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/zswap-update-with-same-value-filled-page-feature.patch
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/SubmitChecklist when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Srividya Desireddy <srividya.dr@xxxxxxxxxxx>
Subject: Documentation/vm/zswap.txt: update with same-value filled page feature
Update zswap document with details on same-value filled pages
identification feature. The usage of zswap.same_filled_pages_enabled
module parameter is explained.
Link: http://lkml.kernel.org/r/20171206114852epcms5p6973b02a9f455d5d3c765eafda0fe2631@epcms5p6
Signed-off-by: Srividya Desireddy <srividya.dr@xxxxxxxxxxx>
Acked-by: Dan Streetman <ddstreet@xxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
Documentation/vm/zswap.txt | 22 +++++++++++++++++++++-
1 file changed, 21 insertions(+), 1 deletion(-)
diff -puN Documentation/vm/zswap.txt~zswap-update-with-same-value-filled-page-feature Documentation/vm/zswap.txt
--- a/Documentation/vm/zswap.txt~zswap-update-with-same-value-filled-page-feature
+++ a/Documentation/vm/zswap.txt
@@ -98,5 +98,25 @@ request is made for a page in an old zpo
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 remain stored
+unchanged in zswap until they are either 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.
_
Patches currently in -mm which might be from srividya.dr@xxxxxxxxxxx are
zswap-same-filled-pages-handling.patch
zswap-same-filled-pages-handling-v2.patch
zswap-update-with-same-value-filled-page-feature.patch
--
To unsubscribe from this list: send the line "unsubscribe mm-commits" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
