[RFC PATCH 0/3] mm/zsmalloc: increase density and reduce memory wastage

From	Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Newsgroups	linux.kernel
Subject	[RFC PATCH 0/3] mm/zsmalloc: increase density and reduce memory wastage
Date	2016-02-18 04:10 +0100
Message-ID	<r3n8B-7Ib-3@gated-at.bofh.it> (permalink)
Organization	linux.* mail to news gateway

Show all headers | View raw

Hello,

 RFC

 ->huge classes are evil, and zsmalloc knows the watermark after which classes
are considered to be ->huge -- every object stored consumes the entire zspage
(which consist of a single order-0 page). zram, however, has its own statically
defined watermark for `bad' compression and stores every object larger than
this watermark as a PAGE_SIZE, object, IOW, to a ->huge class, this results
in increased memory consumption and memory wastage. And zram's 'bad' watermark
is much lower than zsmalloc. Apart from that, 'bad' compressions are not so rare,
on some of my tests 41% of writes result in 'bad' compressions.

This patch set inverts this 'huge class watermark' enforcement, it's zsmalloc
that knows better, not zram.

I did a number of tests (see 0003 commit message) and memory savings were around
36MB and 51MB (depending on zsmalloc configuration).

I also copied a linux-next directory (with object files, du -sh  2.5G)
and (ZS_MAX_PAGES_PER_ZSPAGE=5) memory saving were around 17-20MB.



Sergey Senozhatsky (3):
  mm/zsmalloc: introduce zs_get_huge_class_size_watermark()
  zram: use zs_get_huge_class_size_watermark()
  mm/zsmalloc: change ZS_MAX_PAGES_PER_ZSPAGE

 drivers/block/zram/zram_drv.c |  2 +-
 drivers/block/zram/zram_drv.h |  6 ------
 include/linux/zsmalloc.h      |  2 ++
 mm/zsmalloc.c                 | 21 +++++++++++++++++----
 4 files changed, 20 insertions(+), 11 deletions(-)

-- 
2.7.1

Back to linux.kernel | Previous | Next — Next in thread | Find similar | Unroll thread

Thread

[RFC PATCH 0/3] mm/zsmalloc: increase density and reduce memory wastage Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2016-02-18 04:10 +0100
  [RFC PATCH 2/3] zram: use zs_get_huge_class_size_watermark() Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2016-02-18 04:10 +0100
  [RFC PATCH 1/3] mm/zsmalloc: introduce zs_get_huge_class_size_watermark() Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2016-02-18 04:10 +0100
  [RFC PATCH 3/3] mm/zsmalloc: change ZS_MAX_PAGES_PER_ZSPAGE Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2016-02-18 04:10 +0100
    Re: [RFC PATCH 3/3] mm/zsmalloc: change ZS_MAX_PAGES_PER_ZSPAGE Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2016-02-18 05:50 +0100
      Re: [RFC PATCH 3/3] mm/zsmalloc: change ZS_MAX_PAGES_PER_ZSPAGE Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2016-02-18 05:50 +0100
      Re: [RFC PATCH 3/3] mm/zsmalloc: change ZS_MAX_PAGES_PER_ZSPAGE Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2016-02-18 06:10 +0100
    Re: [RFC PATCH 3/3] mm/zsmalloc: change ZS_MAX_PAGES_PER_ZSPAGE Joonsoo Kim <js1304@gmail.com> - 2016-02-18 09:30 +0100
      Re: [RFC PATCH 3/3] mm/zsmalloc: change ZS_MAX_PAGES_PER_ZSPAGE Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2016-02-18 11:00 +0100
        Re: [RFC PATCH 3/3] mm/zsmalloc: change ZS_MAX_PAGES_PER_ZSPAGE Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2016-02-18 11:20 +0100
          Re: [RFC PATCH 3/3] mm/zsmalloc: change ZS_MAX_PAGES_PER_ZSPAGE Joonsoo Kim <js1304@gmail.com> - 2016-02-19 02:30 +0100
            Re: [RFC PATCH 3/3] mm/zsmalloc: change ZS_MAX_PAGES_PER_ZSPAGE Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2016-02-19 05:20 +0100
            Re: [RFC PATCH 3/3] mm/zsmalloc: change ZS_MAX_PAGES_PER_ZSPAGE Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2016-02-19 05:20 +0100
              Re: [RFC PATCH 3/3] mm/zsmalloc: change ZS_MAX_PAGES_PER_ZSPAGE Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2016-02-19 05:50 +0100
                Re: [RFC PATCH 3/3] mm/zsmalloc: change ZS_MAX_PAGES_PER_ZSPAGE Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2016-02-19 06:40 +0100
                Re: [RFC PATCH 3/3] mm/zsmalloc: change ZS_MAX_PAGES_PER_ZSPAGE Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2016-02-19 07:00 +0100

csiph-web