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8e19d540d1
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> |
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| .. | ||
| Kconfig | ||
| Makefile | ||
| zcomp.c | ||
| zcomp.h | ||
| zram_drv.c | ||
| zram_drv.h | ||