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[PATCH] zone_reclaim: additional comments and cleanup
Add some comments to explain how zone reclaim works. And it fixes the following issues: - PF_SWAPWRITE needs to be set for RECLAIM_SWAP to be able to write out pages to swap. Currently RECLAIM_SWAP may not do that. - remove setting nr_reclaimed pages after slab reclaim since the slab shrinking code does not use that and the nr_reclaimed pages is just right for the intended follow up action. Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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parent
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18
mm/vmscan.c
18
mm/vmscan.c
@ -1887,6 +1887,7 @@ int zone_reclaim_interval __read_mostly = 30*HZ;
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*/
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static int __zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order)
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{
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/* Minimum pages needed in order to stay on node */
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const unsigned long nr_pages = 1 << order;
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struct task_struct *p = current;
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struct reclaim_state reclaim_state;
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@ -1924,9 +1925,12 @@ static int __zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order)
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if (nr_reclaimed < nr_pages && (zone_reclaim_mode & RECLAIM_SLAB)) {
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/*
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* shrink_slab does not currently allow us to determine
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* how many pages were freed in the zone. So we just
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* shake the slab and then go offnode for a single allocation.
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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 just shake the slab
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* a bit and then go off node for this particular allocation
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* despite possibly having freed enough memory to allocate in
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* this zone. If we freed local memory then the next
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* allocations will be local again.
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*
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* shrink_slab will free memory on all zones and may take
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* a long time.
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@ -1937,8 +1941,14 @@ static int __zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order)
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p->reclaim_state = NULL;
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current->flags &= ~(PF_MEMALLOC | PF_SWAPWRITE);
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if (nr_reclaimed == 0)
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if (nr_reclaimed == 0) {
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/*
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* We were unable to reclaim enough pages to stay on node. We
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* now allow off node accesses for a certain time period before
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* trying again to reclaim pages from the local zone.
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*/
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zone->last_unsuccessful_zone_reclaim = jiffies;
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}
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return nr_reclaimed >= nr_pages;
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}
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