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Re: [RFC PATCH 3/3] mm/zsmalloc: change ZS_MAX_PAGES_PER_ZSPAGE

From Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Newsgroups linux.kernel
Subject Re: [RFC PATCH 3/3] mm/zsmalloc: change ZS_MAX_PAGES_PER_ZSPAGE
Date 2016-02-18 06:10 +0100
Message-ID <r3p0J-Bk-7@gated-at.bofh.it> (permalink)
References <r3n8B-7Ib-3@gated-at.bofh.it> <r3n8C-7Ib-15@gated-at.bofh.it> <r3oHn-fk-1@gated-at.bofh.it>
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On (02/18/16 13:41), Sergey Senozhatsky wrote:
> diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
> index 0c9f117..d5252d1 100644
> --- a/mm/zsmalloc.c
> +++ b/mm/zsmalloc.c
> @@ -73,12 +73,6 @@
>   */
>  #define ZS_ALIGN               8
>  
> -/*
> - * A single 'zspage' is composed of up ZS_MAX_PAGES_PER_ZSPAGE discontiguous
> - * 0-order (single) pages.
> - */
> -#define ZS_MAX_PAGES_PER_ZSPAGE        6
> -
>  #define ZS_HANDLE_SIZE (sizeof(unsigned long))
>  
>  /*
> @@ -149,6 +143,21 @@
>  #define ZS_SIZE_CLASS_DELTA    (PAGE_SIZE >> 8)
>  
>  /*
> + * We want to have at least this number of ->huge classes.
> + */
> +#define ZS_MIN_HUGE_CLASSES_NUM        32
> +/*
> + * A single 'zspage' is composed of up ZS_MAX_PAGES_PER_ZSPAGE discontiguous
> + * 0-order (single) pages.
> + *
> + * The smallest huge class will have CLASS_SIZE * SIZE_CLASS_DELTA of
> + * wasted space, calculate how many pages we need to fit a CLASS_SIZE
> + * object there and, thus, to save a additional zspage.
> + */
> +#define ZS_MAX_PAGES_PER_ZSPAGE        \
> +       (PAGE_SIZE / (ZS_MIN_HUGE_CLASSES_NUM * ZS_SIZE_CLASS_DELTA))
> +
> +/*
>   * We do not maintain any list for completely empty or full pages
>   */
>  enum fullness_group {

and the difference between ZS_MIN_HUGE_CLASSES_NUM 57 (BASE number of
->huge classes) and ZS_MIN_HUGE_CLASSES_NUM 32 is:

ZS_MIN_HUGE_CLASSES_NUM 57 (BASE)
1151078400 575501415 621494272        0 621494272       17        0        1
1151074304 575499905 621477888        0 621477888       17        0        1
1151074304 575516318 621363200        0 621363200       17        0        1
1151078400 575558182 621346816        0 621346816       17        0        1
1151078400 575599320 621531136        0 621531136       17        0        1

ZS_MIN_HUGE_CLASSES_NUM 32
1151074304 575483112 594194432        0 594194432       17        0        1
1151074304 575521895 593678336        0 593678336       17        0        1
1151074304 575570453 594173952        0 594173952       17        0        1
1151074304 575461842 594010112        0 594010112       17        0        1
1151074304 575537116 593879040        0 593879040       17        0        1


around 26MB of order-0 pages.

	-ss

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[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

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