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
WARNING: multiple messages have this Message-ID (diff)
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 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
next prev parent reply other threads:[~2017-03-01 13:55 UTC|newest] Thread overview: 80+ 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 ` Johannes Weiner 2017-02-28 21:39 ` [PATCH 1/9] mm: fix 100% CPU kswapd busyloop on unreclaimable nodes Johannes Weiner 2017-02-28 21:39 ` Johannes Weiner 2017-03-02 3:23 ` Hillf Danton 2017-03-02 3:23 ` Hillf Danton 2017-03-02 23:30 ` Shakeel Butt 2017-03-02 23:30 ` Shakeel Butt 2017-03-03 1:26 ` Minchan Kim 2017-03-03 1:26 ` Minchan Kim 2017-03-03 7:59 ` Michal Hocko 2017-03-03 7:59 ` Michal Hocko 2017-03-06 1:37 ` Minchan Kim 2017-03-06 1:37 ` Minchan Kim 2017-03-06 16:24 ` Johannes Weiner 2017-03-06 16:24 ` Johannes Weiner 2017-03-07 0:59 ` Hillf Danton 2017-03-07 0:59 ` Hillf Danton 2017-03-07 7:28 ` Minchan Kim 2017-03-07 7:28 ` Minchan Kim 2017-03-07 10:17 ` Michal Hocko 2017-03-07 10:17 ` Michal Hocko 2017-03-07 16:56 ` Johannes Weiner 2017-03-07 16:56 ` Johannes Weiner 2017-03-09 14:20 ` Mel Gorman 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 2017-02-28 21:40 ` Johannes Weiner 2017-03-01 15:02 ` Michal Hocko 2017-03-01 15:02 ` Michal Hocko 2017-03-02 3:25 ` Hillf Danton 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 2017-02-28 21:40 ` Johannes Weiner 2017-03-01 15:06 ` Michal Hocko 2017-03-01 15:06 ` Michal Hocko 2017-03-01 15:17 ` Mel Gorman 2017-03-01 15:17 ` Mel Gorman 2017-03-02 3:27 ` Hillf Danton 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 2017-02-28 21:40 ` Johannes Weiner 2017-03-01 15:14 ` Michal Hocko 2017-03-01 15:14 ` Michal Hocko 2017-03-02 3:28 ` Hillf Danton 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 2017-02-28 21:40 ` Johannes Weiner 2017-03-01 15:21 ` Michal Hocko 2017-03-01 15:21 ` Michal Hocko 2017-03-02 3:31 ` Hillf Danton 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 2017-02-28 21:40 ` Johannes Weiner 2017-03-01 15:40 ` Michal Hocko 2017-03-01 15:40 ` Michal Hocko 2017-03-01 17:36 ` Johannes Weiner 2017-03-01 17:36 ` Johannes Weiner 2017-03-01 19:13 ` Michal Hocko 2017-03-01 19:13 ` Michal Hocko 2017-03-02 3:32 ` Hillf Danton 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 2017-02-28 21:40 ` Johannes Weiner 2017-03-01 15:41 ` Michal Hocko 2017-03-01 15:41 ` Michal Hocko 2017-03-02 3:34 ` Hillf Danton 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 2017-02-28 21:40 ` Johannes Weiner 2017-03-01 15:51 ` Michal Hocko 2017-03-01 15:51 ` Michal Hocko 2017-03-02 3:36 ` Hillf Danton 2017-03-02 3:36 ` Hillf Danton 2017-02-28 21:40 ` Johannes Weiner [this message] 2017-02-28 21:40 ` [PATCH 9/9] mm: remove unnecessary back-off function when retrying page reclaim Johannes Weiner 2017-03-01 14:56 ` Michal Hocko 2017-03-01 14:56 ` Michal Hocko 2017-03-02 3:37 ` Hillf Danton 2017-03-02 3:37 ` Hillf Danton
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