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68 lines
2.4 KiB
68 lines
2.4 KiB
From: Nick Piggin <npiggin@suse.de>
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Subject: be more aggressive with zone reclaims
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References: bnc#476525
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Patch-mainline: no
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The zone reclaim design is not very good for parallel allocations.
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The primary problem is that only one thread is allowed to perform
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zone-reclaim at a time. If another thread needs memory from that
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zone/node, then its zone-reclaim will fail and it will be forced
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to fall back to allocating from another zone.
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Additionally, the default zone reclaim priority is insufficient
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for massively parallel allocations. Lower ZONE_RECLAIM_PRIORITY
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to fix it. This can result in higher latency spikes, but similar
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kind of page allocation latency can often be encountered as
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normal part of page reclaim when pagecache fills memory.
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Signed-off-by: Petr Tesarik <ptesarik@suse.cz>
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---
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mm/vmscan.c | 13 ++++---------
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1 file changed, 4 insertions(+), 9 deletions(-)
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--- a/mm/vmscan.c
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+++ b/mm/vmscan.c
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@@ -2515,7 +2515,7 @@ int zone_reclaim_mode __read_mostly;
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* of a node considered for each zone_reclaim. 4 scans 1/16th of
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* a zone.
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*/
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-#define ZONE_RECLAIM_PRIORITY 4
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+#define ZONE_RECLAIM_PRIORITY 0
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/*
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* Percentage of pages in a zone that must be unmapped for zone_reclaim to
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@@ -2620,6 +2620,8 @@ static int __zone_reclaim(struct zone *z
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slab_reclaimable = zone_page_state(zone, NR_SLAB_RECLAIMABLE);
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if (slab_reclaimable > zone->min_slab_pages) {
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+ unsigned long lru_pages = zone_reclaimable_pages(zone);
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+
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/*
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* shrink_slab() does not currently allow us to determine how
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* many pages were freed in this zone. So we take the current
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@@ -2630,10 +2632,7 @@ static int __zone_reclaim(struct zone *z
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* Note that shrink_slab will free memory on all zones and may
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* take a long time.
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*/
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- while (shrink_slab(sc.nr_scanned, gfp_mask, order) &&
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- zone_page_state(zone, NR_SLAB_RECLAIMABLE) >
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- slab_reclaimable - nr_pages)
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- ;
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+ shrink_slab(sc.nr_scanned, gfp_mask, lru_pages);
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/*
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* Update nr_reclaimed by the number of slab pages we
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@@ -2687,11 +2686,7 @@ int zone_reclaim(struct zone *zone, gfp_
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if (node_state(node_id, N_CPU) && node_id != numa_node_id())
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return ZONE_RECLAIM_NOSCAN;
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- if (zone_test_and_set_flag(zone, ZONE_RECLAIM_LOCKED))
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- return ZONE_RECLAIM_NOSCAN;
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-
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ret = __zone_reclaim(zone, gfp_mask, order);
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- zone_clear_flag(zone, ZONE_RECLAIM_LOCKED);
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if (!ret)
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count_vm_event(PGSCAN_ZONE_RECLAIM_FAILED);
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