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Subject[PATCH 1/1] page_alloc.c: Slightly improve the logic in __alloc_pages_high_priority
Date
The loop in __alloc_pages_high_priority() seems to be checking for
(!page) and (gfp_mask & __GFP_NOFAIL) multiple times.

In fact, we don't really need to check (gfp_mask & __GFP_NOFAIL)
for every iteration of the loop as the gfp_mask remains constant.

Slightly improve the logic in __alloc_pages_high_priority() to
eliminate these multiple condition checks.

Signed-off-by: Kautuk Consul <consul.kautuk@gmail.com>
---
mm/page_alloc.c | 13 +++++++++----
1 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index a13ded1..6bb8b6d 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -2114,14 +2114,19 @@ __alloc_pages_high_priority(gfp_t gfp_mask, unsigned int order,
{
struct page *page;

- do {
- page = get_page_from_freelist(gfp_mask, nodemask, order,
+ page = get_page_from_freelist(gfp_mask, nodemask, order,
zonelist, high_zoneidx, ALLOC_NO_WATERMARKS,
preferred_zone, migratetype);

- if (!page && gfp_mask & __GFP_NOFAIL)
+ if (gfp_mask & __GFP_NOFAIL) {
+ while (!page) {
wait_iff_congested(preferred_zone, BLK_RW_ASYNC, HZ/50);
- } while (!page && (gfp_mask & __GFP_NOFAIL));
+
+ page = get_page_from_freelist(gfp_mask, nodemask, order,
+ zonelist, high_zoneidx, ALLOC_NO_WATERMARKS,
+ preferred_zone, migratetype);
+ }
+ }

return page;
}
--
1.7.5.4


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