From: Sangwoo Park Date: Wed, 3 May 2017 21:55:56 +0000 (-0700) Subject: zram: reduce load operation in page_same_filled X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=f0fe9984656604ea8effd5ff82709ff8ce1f954b;p=GitHub%2Fmoto-9609%2Fandroid_kernel_motorola_exynos9610.git zram: reduce load operation in page_same_filled In page_same_filled function, all elements in the page is compared with next index value. The current comparison routine compares the (i)th and (i+1)th values of the page. In this case, two load operaions occur for each comparison. But if we store first value of the page stores at 'val' variable and using it to compare with others, the load opearation is reduced. It reduce load operation per page by up to 64times. Link: http://lkml.kernel.org/r/1488428104-7257-1-git-send-email-sangwoo2.park@lge.com Signed-off-by: Sangwoo Park Reviewed-by: Sergey Senozhatsky Acked-by: Minchan Kim Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c index d303334e3da3..debee952dcc1 100644 --- a/drivers/block/zram/zram_drv.c +++ b/drivers/block/zram/zram_drv.c @@ -195,15 +195,17 @@ static bool page_same_filled(void *ptr, unsigned long *element) { unsigned int pos; unsigned long *page; + unsigned long val; page = (unsigned long *)ptr; + val = page[0]; - for (pos = 0; pos < PAGE_SIZE / sizeof(*page) - 1; pos++) { - if (page[pos] != page[pos + 1]) + for (pos = 1; pos < PAGE_SIZE / sizeof(*page); pos++) { + if (val != page[pos]) return false; } - *element = page[pos]; + *element = val; return true; }