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authorSangwoo Park <sangwoo2.park@lge.com>2017-05-03 14:55:56 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2017-05-03 15:52:11 -0700
commitf0fe9984656604ea8effd5ff82709ff8ce1f954b (patch)
tree8b2998a6041eb33b592ed10abd551a7a29fc43b6 /drivers/block
parent302128dce142d780417aa548bfd7ef4dfb89fa80 (diff)
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 <sangwoo2.park@lge.com> Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Acked-by: Minchan Kim <minchan@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'drivers/block')
-rw-r--r--drivers/block/zram/zram_drv.c8
1 files changed, 5 insertions, 3 deletions
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;
}