diff options
| author |   zhouxianrong <zhouxianrong@huawei.com> | 2017-02-24 14:59:27 -0800 |
|---|---|---|
| committer |   Linus Torvalds <torvalds@linux-foundation.org> | 2017-02-24 17:46:56 -0800 |
| commit | 8e19d540d107ee897eb9a874844060c94e2376c0 (patch) | |
| tree | a268e406f52137cf0f81150c8f27b0c9100c6bfb /drivers/block/zram/zram_drv.h | |
| parent | mm/page-writeback.c: place "not" inside of unlikely() statement in wb_domain_writeout_inc() (diff) | |
| download | linux-dev-8e19d540d107ee897eb9a874844060c94e2376c0.tar.xz linux-dev-8e19d540d107ee897eb9a874844060c94e2376c0.zip | |
zram: extend zero pages to same element pages
The idea is that without doing more calculations we extend zero pages to
same element pages for zram. zero page is special case of same element
page with zero element.
1. the test is done under android 7.0
2. startup too many applications circularly
3. sample the zero pages, same pages (none-zero element)
and total pages in function page_zero_filled
the result is listed as below:
ZERO SAME TOTAL
36214 17842 598196
ZERO/TOTAL SAME/TOTAL (ZERO+SAME)/TOTAL ZERO/SAME
AVERAGE 0.060631909 0.024990816 0.085622726 2.663825038
STDEV 0.00674612 0.005887625 0.009707034 2.115881328
MAX 0.069698422 0.030046087 0.094975336 7.56043956
MIN 0.03959586 0.007332205 0.056055193 1.928985507
from the above data, the benefit is about 2.5% and up to 3% of total
swapout pages.
The defect of the patch is that when we recovery a page from non-zero
element the operations are low efficient for partial read.
This patch extends zero_page to same_page so if there is any user to
have monitored zero_pages, he will be surprised if the number is
increased but it's not harmful, I believe.
[minchan@kernel.org: do not free same element pages in zram_meta_free]
Link: http://lkml.kernel.org/r/20170207065741.GA2567@bbox
Link: http://lkml.kernel.org/r/1483692145-75357-1-git-send-email-zhouxianrong@huawei.com
Link: http://lkml.kernel.org/r/1486307804-27903-1-git-send-email-minchan@kernel.org
Signed-off-by: zhouxianrong <zhouxianrong@huawei.com>
Signed-off-by: Minchan Kim <minchan@kernel.org>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to '')
| -rw-r--r-- | drivers/block/zram/zram_drv.h | 9 |
1 files changed, 6 insertions, 3 deletions
diff --git a/drivers/block/zram/zram_drv.h b/drivers/block/zram/zram_drv.h index 2692554b7737..caeff51f1571 100644 --- a/drivers/block/zram/zram_drv.h +++ b/drivers/block/zram/zram_drv.h @@ -61,7 +61,7 @@ static const size_t max_zpage_size = PAGE_SIZE / 4 * 3; /* Flags for zram pages (table[page_no].value) */ enum zram_pageflags { /* Page consists entirely of zeros */ - ZRAM_ZERO = ZRAM_FLAG_SHIFT, + ZRAM_SAME = ZRAM_FLAG_SHIFT, ZRAM_ACCESS, /* page is now accessed */ __NR_ZRAM_PAGEFLAGS, @@ -71,7 +71,10 @@ enum zram_pageflags { /* Allocated for each disk page */ struct zram_table_entry { - unsigned long handle; + union { + unsigned long handle; + unsigned long element; + }; unsigned long value; }; @@ -83,7 +86,7 @@ struct zram_stats { atomic64_t failed_writes; /* can happen when memory is too low */ atomic64_t invalid_io; /* non-page-aligned I/O requests */ atomic64_t notify_free; /* no. of swap slot free notifications */ - atomic64_t zero_pages; /* no. of zero filled pages */ + atomic64_t same_pages; /* no. of same element filled pages */ atomic64_t pages_stored; /* no. of pages currently stored */ atomic_long_t max_used_pages; /* no. of maximum pages stored */ atomic64_t writestall; /* no. of write slow paths */ |