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Re: [RFC 0/4] ZRAM: make it just store the high compression rate page

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Hello,

On (08/22/16 16:25), Hui Zhu wrote:
> 
> Current ZRAM just can store all pages even if the compression rate
> of a page is really low.  So the compression rate of ZRAM is out of
> control when it is running.
> In my part, I did some test and record with ZRAM.  The compression rate
> is about 40%.
> 
> This series of patches make ZRAM can just store the page that the
> compressed size is smaller than a value.
> With these patches, I set the value to 2048 and did the same test with
> before.  The compression rate is about 20%.  The times of lowmemorykiller
> also decreased.

I haven't looked at the patches in details yet. can you educate me a bit?
is your test stable? why the number of lowmemorykill-s has decreased?
... or am reading "The times of lowmemorykiller also decreased" wrong?

suppose you have X pages that result in bad compression size (from zram
point of view). zram stores such pages uncompressed, IOW we have no memory
savings - swapped out page lands in zsmalloc PAGE_SIZE class. now you
don't try to store those pages in zsmalloc, but keep them as unevictable.
so the page still occupies PAGE_SIZE; no memory saving again. why did it
improve LMK?

	-ss

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[RFC 0/4] ZRAM: make it just store the high compression rate page Hui Zhu <zhuhui@xiaomi.com> - 2016-08-22 10:50 +0200
  [RFC 4/4] vmscan.c: zram: add non swap support for shmem file pages Hui Zhu <zhuhui@xiaomi.com> - 2016-08-22 10:50 +0200
  Re: [RFC 0/4] ZRAM: make it just store the high compression rate page Minchan Kim <minchan@kernel.org> - 2016-08-24 03:10 +0200
    Re: [RFC 0/4] ZRAM: make it just store the high compression rate page Hui Zhu <teawater@gmail.com> - 2016-08-24 04:00 +0200
  Re: [RFC 0/4] ZRAM: make it just store the high compression rate page Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2016-08-25 08:20 +0200
    Re: [RFC 0/4] ZRAM: make it just store the high compression rate page Hui Zhu <teawater@gmail.com> - 2016-08-25 10:30 +0200
      Re: [RFC 0/4] ZRAM: make it just store the high compression rate page Minchan Kim <minchan@kernel.org> - 2016-09-05 04:20 +0200
        Re: [RFC 0/4] ZRAM: make it just store the high compression rate page Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2016-09-05 06:00 +0200
        Re: [RFC 0/4] ZRAM: make it just store the high compression rate page Hui Zhu <teawater@gmail.com> - 2016-09-05 07:20 +0200
          Re: [RFC 0/4] ZRAM: make it just store the high compression rate page Minchan Kim <minchan@kernel.org> - 2016-09-05 08:00 +0200
            Re: [RFC 0/4] ZRAM: make it just store the high compression rate page Hui Zhu <teawater@gmail.com> - 2016-09-05 08:10 +0200
  Re: [RFC 0/4] ZRAM: make it just store the high compression rate page Minchan Kim <minchan@kernel.org> - 2016-09-05 04:20 +0200

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