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.
Signed-off-by: Johannes Weiner <han...@cmpxchg.org>
---
mm/page_alloc.c | 15 ++++++---------
1 file changed, 6 insertions(+), 9 deletions(-)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 9ac639864bed..223644afed28 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -3511,11 +3511,10 @@ 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.
*/
@@ -3560,13 +3559,11 @@ 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);
--
2.11.1
