Re: kswapd craziness in 3.7
From: Jiri Slaby <hidden>
Date: 2012-12-08 10:35:54
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On 12/04/2012 05:11 PM, Johannes Weiner wrote:
On Tue, Dec 04, 2012 at 10:15:09AM +0100, Jiri Slaby wrote:quoted
It does not apply to -next :/. Should I try anything else?The COMPACTION_BUILD changed to IS_ENABLED(CONFIG_COMPACTION), below is a -next patch. I hope you don't run into other problems that come out of -next craziness, because Linus is kinda waiting for this to be resolved to release 3.8. If you've always tested against -next so far and it worked otherwise, don't change the environment now, please. If you just started, it would make more sense to test based on 3.7-rc8. Thanks! --- From: Johannes Weiner <hannes@cmpxchg.org> Subject: [patch] mm: vmscan: do not keep kswapd looping forever due to individual uncompactable zones When a zone meets its high watermark and is compactable in case of higher order allocations, it contributes to the percentage of the node's memory that is considered balanced. This requirement, that a node be only partially balanced, came about when kswapd was desparately trying to balance tiny zones when all bigger zones in the node had plenty of free memory. Arguably, the same should apply to compaction: if a significant part of the node is balanced enough to run compaction, do not get hung up on that tiny zone that might never get in shape. When the compaction logic in kswapd is reached, we know that at least 25% of the node's memory is balanced properly for compaction (see zone_balanced and pgdat_balanced). Remove the individual zone checks that restart the kswapd cycle. Otherwise, we may observe more endless looping in kswapd where the compaction code loops back to reclaim because of a single zone and reclaim does nothing because the node is considered balanced overall. Reported-by: Thorsten Leemhuis <redacted> Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Looks like it's gone with this patch now. Hopefully the send button won't trigger the issue the same as the last time :).
quoted hunk ↗ jump to hunk
--- mm/vmscan.c | 16 ---------------- 1 file changed, 16 deletions(-)diff --git a/mm/vmscan.c b/mm/vmscan.c index 3b0aef4..486100f 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c@@ -2806,22 +2806,6 @@ static unsigned long balance_pgdat(pg_data_t *pgdat, int order, if (!populated_zone(zone)) continue; - if (zone->all_unreclaimable && - sc.priority != DEF_PRIORITY) - continue; - - /* Would compaction fail due to lack of free memory? */ - if (IS_ENABLED(CONFIG_COMPACTION) && - compaction_suitable(zone, order) == COMPACT_SKIPPED) - goto loop_again; - - /* Confirm the zone is balanced for order-0 */ - if (!zone_watermark_ok(zone, 0, - high_wmark_pages(zone), 0, 0)) { - order = sc.order = 0; - goto loop_again; - } - /* Check if the memory needs to be defragmented. */ if (zone_watermark_ok(zone, order, low_wmark_pages(zone), *classzone_idx, 0))
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