From: Johannes Weiner <hannes@cmpxchg.org>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Jia He <hejianet@gmail.com>, Michal Hocko <mhocko@suse.cz>,
Mel Gorman <mgorman@suse.de>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
kernel-team@fb.com
Subject: [PATCH 9/9] mm: remove unnecessary back-off function when retrying page reclaim
Date: Tue, 28 Feb 2017 16:40:07 -0500 [thread overview]
Message-ID: <20170228214007.5621-10-hannes@cmpxchg.org> (raw)
In-Reply-To: <20170228214007.5621-1-hannes@cmpxchg.org>
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 <hannes@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
next prev parent reply other threads:[~2017-03-01 13:55 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-02-28 21:39 [PATCH 0/9] mm: kswapd spinning on unreclaimable nodes - fixes and cleanups Johannes Weiner
2017-02-28 21:39 ` [PATCH 1/9] mm: fix 100% CPU kswapd busyloop on unreclaimable nodes Johannes Weiner
2017-03-02 3:23 ` Hillf Danton
2017-03-02 23:30 ` Shakeel Butt
2017-03-03 1:26 ` Minchan Kim
2017-03-03 7:59 ` Michal Hocko
2017-03-06 1:37 ` Minchan Kim
2017-03-06 16:24 ` Johannes Weiner
2017-03-07 0:59 ` Hillf Danton
2017-03-07 7:28 ` Minchan Kim
2017-03-07 10:17 ` Michal Hocko
2017-03-07 16:56 ` Johannes Weiner
2017-03-09 14:20 ` Mel Gorman
2017-02-28 21:40 ` [PATCH 2/9] mm: fix check for reclaimable pages in PF_MEMALLOC reclaim throttling Johannes Weiner
2017-03-01 15:02 ` Michal Hocko
2017-03-02 3:25 ` Hillf Danton
2017-02-28 21:40 ` [PATCH 3/9] mm: remove seemingly spurious reclaimability check from laptop_mode gating Johannes Weiner
2017-03-01 15:06 ` Michal Hocko
2017-03-01 15:17 ` Mel Gorman
2017-03-02 3:27 ` Hillf Danton
2017-02-28 21:40 ` [PATCH 4/9] mm: remove unnecessary reclaimability check from NUMA balancing target Johannes Weiner
2017-03-01 15:14 ` Michal Hocko
2017-03-02 3:28 ` Hillf Danton
2017-02-28 21:40 ` [PATCH 5/9] mm: don't avoid high-priority reclaim on unreclaimable nodes Johannes Weiner
2017-03-01 15:21 ` Michal Hocko
2017-03-02 3:31 ` Hillf Danton
2017-02-28 21:40 ` [PATCH 6/9] mm: don't avoid high-priority reclaim on memcg limit reclaim Johannes Weiner
2017-03-01 15:40 ` Michal Hocko
2017-03-01 17:36 ` Johannes Weiner
2017-03-01 19:13 ` Michal Hocko
2017-03-02 3:32 ` Hillf Danton
2017-02-28 21:40 ` [PATCH 7/9] mm: delete NR_PAGES_SCANNED and pgdat_reclaimable() Johannes Weiner
2017-03-01 15:41 ` Michal Hocko
2017-03-02 3:34 ` Hillf Danton
2017-02-28 21:40 ` [PATCH 8/9] Revert "mm, vmscan: account for skipped pages as a partial scan" Johannes Weiner
2017-03-01 15:51 ` Michal Hocko
2017-03-02 3:36 ` Hillf Danton
2017-02-28 21:40 ` Johannes Weiner [this message]
2017-03-01 14:56 ` [PATCH 9/9] mm: remove unnecessary back-off function when retrying page reclaim Michal Hocko
2017-03-02 3:37 ` Hillf Danton
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