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authorJohannes Weiner <hannes@cmpxchg.org>2017-05-03 14:52:16 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2017-05-03 15:52:08 -0700
commit491d79ae778f24dbf65f1f2178d4744d940d4093 (patch)
treee331158536949076d7b9b155fc663d2525f2fda8 /mm
parent3db65812d68883d1acfd20a9f2bc2cd13a7cd5c5 (diff)
mm: remove unnecessary back-off function when retrying page reclaim
The backoff mechanism is not needed. If we have MAX_RECLAIM_RETRIES loops without progress, we'll OOM anyway; backing off might cut one or two iterations off that in the rare OOM case. If we have intermittent success reclaiming a few pages, the backoff function gets reset also, and so is of little help in these scenarios. We might want a backoff function for when there IS progress, but not enough to be satisfactory. But this isn't that. Remove it. Link: http://lkml.kernel.org/r/20170228214007.5621-10-hannes@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Jia He <hejianet@gmail.com> Cc: Mel Gorman <mgorman@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/page_alloc.c15
1 files changed, 6 insertions, 9 deletions
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 6994f28f769c..f82beddbd96f 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -3515,11 +3515,10 @@ bool gfp_pfmemalloc_allowed(gfp_t gfp_mask)
/*
* Checks whether it makes sense to retry the reclaim to make a forward progress
* for the given allocation request.
- * The reclaim feedback represented by did_some_progress (any progress during
- * the last reclaim round) and no_progress_loops (number of reclaim rounds without
- * any progress in a row) is considered as well as the reclaimable pages on the
- * applicable zone list (with a backoff mechanism which is a function of
- * no_progress_loops).
+ *
+ * We give up when we either have tried MAX_RECLAIM_RETRIES in a row
+ * without success, or when we couldn't even meet the watermark if we
+ * reclaimed all remaining pages on the LRU lists.
*
* Returns true if a retry is viable or false to enter the oom path.
*/
@@ -3564,13 +3563,11 @@ should_reclaim_retry(gfp_t gfp_mask, unsigned order,
bool wmark;
available = reclaimable = zone_reclaimable_pages(zone);
- available -= DIV_ROUND_UP((*no_progress_loops) * available,
- MAX_RECLAIM_RETRIES);
available += zone_page_state_snapshot(zone, NR_FREE_PAGES);
/*
- * Would the allocation succeed if we reclaimed the whole
- * available?
+ * Would the allocation succeed if we reclaimed all
+ * reclaimable pages?
*/
wmark = __zone_watermark_ok(zone, order, min_wmark,
ac_classzone_idx(ac), alloc_flags, available);