mm: vmscan: do not reclaim from kswapd if there is any eligible zone
kswapd scans from highest to lowest for a zone that requires balancing. This was necessary when reclaim was per-zone to fairly age pages on lower zones. Now that we are reclaiming on a per-node basis, any eligible zone can be used and pages will still be aged fairly. This patch avoids reclaiming excessively unless buffer_heads are over the limit and it's necessary to reclaim from a higher zone than requested by the waker of kswapd to relieve low memory pressure. [hillf.zj@alibaba-inc.com: Force kswapd reclaim no more than needed] Link: http://lkml.kernel.org/r/1466518566-30034-12-git-send-email-mgorman@techsingularity.net Link: http://lkml.kernel.org/r/1467970510-21195-13-git-send-email-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Signed-off-by: Hillf Danton <hillf.zj@alibaba-inc.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@surriel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
parent
6256c6b499
commit
86c79f6b54
59
mm/vmscan.c
59
mm/vmscan.c
|
@ -3144,31 +3144,39 @@ static int balance_pgdat(pg_data_t *pgdat, int order, int classzone_idx)
|
|||
|
||||
sc.nr_reclaimed = 0;
|
||||
|
||||
/* Scan from the highest requested zone to dma */
|
||||
for (i = classzone_idx; i >= 0; i--) {
|
||||
zone = pgdat->node_zones + i;
|
||||
if (!populated_zone(zone))
|
||||
continue;
|
||||
/*
|
||||
* If the number of buffer_heads in the machine exceeds the
|
||||
* maximum allowed level then reclaim from all zones. This is
|
||||
* not specific to highmem as highmem may not exist but it is
|
||||
* it is expected that buffer_heads are stripped in writeback.
|
||||
*/
|
||||
if (buffer_heads_over_limit) {
|
||||
for (i = MAX_NR_ZONES - 1; i >= 0; i--) {
|
||||
zone = pgdat->node_zones + i;
|
||||
if (!populated_zone(zone))
|
||||
continue;
|
||||
|
||||
/*
|
||||
* If the number of buffer_heads in the machine
|
||||
* exceeds the maximum allowed level and this node
|
||||
* has a highmem zone, force kswapd to reclaim from
|
||||
* it to relieve lowmem pressure.
|
||||
*/
|
||||
if (buffer_heads_over_limit && is_highmem_idx(i)) {
|
||||
classzone_idx = i;
|
||||
break;
|
||||
}
|
||||
|
||||
if (!zone_balanced(zone, order, 0)) {
|
||||
classzone_idx = i;
|
||||
break;
|
||||
}
|
||||
}
|
||||
|
||||
if (i < 0)
|
||||
goto out;
|
||||
/*
|
||||
* Only reclaim if there are no eligible zones. Check from
|
||||
* high to low zone as allocations prefer higher zones.
|
||||
* Scanning from low to high zone would allow congestion to be
|
||||
* cleared during a very small window when a small low
|
||||
* zone was balanced even under extreme pressure when the
|
||||
* overall node may be congested.
|
||||
*/
|
||||
for (i = classzone_idx; i >= 0; i--) {
|
||||
zone = pgdat->node_zones + i;
|
||||
if (!populated_zone(zone))
|
||||
continue;
|
||||
|
||||
if (zone_balanced(zone, sc.order, classzone_idx))
|
||||
goto out;
|
||||
}
|
||||
|
||||
/*
|
||||
* Do some background aging of the anon list, to give
|
||||
|
@ -3213,19 +3221,6 @@ static int balance_pgdat(pg_data_t *pgdat, int order, int classzone_idx)
|
|||
if (try_to_freeze() || kthread_should_stop())
|
||||
break;
|
||||
|
||||
/*
|
||||
* Stop reclaiming if any eligible zone is balanced and clear
|
||||
* node writeback or congested.
|
||||
*/
|
||||
for (i = 0; i <= classzone_idx; i++) {
|
||||
zone = pgdat->node_zones + i;
|
||||
if (!populated_zone(zone))
|
||||
continue;
|
||||
|
||||
if (zone_balanced(zone, sc.order, classzone_idx))
|
||||
goto out;
|
||||
}
|
||||
|
||||
/*
|
||||
* Raise priority if scanning rate is too low or there was no
|
||||
* progress in reclaiming pages
|
||||
|
|
Loading…
Reference in a new issue