Messages in this thread | | | Subject | Re: [PATCH 12/27] mm, vmscan: Make shrink_node decisions more node-centric | From | Vlastimil Babka <> | Date | Thu, 16 Jun 2016 15:35:15 +0200 |
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On 06/09/2016 08:04 PM, Mel Gorman wrote: > Earlier patches focused on having direct reclaim and kswapd use data that > is node-centric for reclaiming but shrink_node() itself still uses too much > zone information. This patch removes unnecessary zone-based information > with the most important decision being whether to continue reclaim or > not. Some memcg APIs are adjusted as a result even though memcg itself > still uses some zone information. > > Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
[...]
> @@ -2372,21 +2374,27 @@ static inline bool should_continue_reclaim(struct zone *zone, > * inactive lists are large enough, continue reclaiming > */ > pages_for_compaction = (2UL << sc->order); > - inactive_lru_pages = node_page_state(zone->zone_pgdat, NR_INACTIVE_FILE); > + inactive_lru_pages = node_page_state(pgdat, NR_INACTIVE_FILE); > if (get_nr_swap_pages() > 0) > - inactive_lru_pages += node_page_state(zone->zone_pgdat, NR_INACTIVE_ANON); > + inactive_lru_pages += node_page_state(pgdat, NR_INACTIVE_ANON); > if (sc->nr_reclaimed < pages_for_compaction && > inactive_lru_pages > pages_for_compaction) > return true; > > /* If compaction would go ahead or the allocation would succeed, stop */ > - switch (compaction_suitable(zone, sc->order, 0, 0)) { > - case COMPACT_PARTIAL: > - case COMPACT_CONTINUE: > - return false; > - default: > - return true; > + for (z = 0; z <= sc->reclaim_idx; z++) { > + struct zone *zone = &pgdat->node_zones[z]; > + > + switch (compaction_suitable(zone, sc->order, 0, 0)) {
Using 0 for classzone_idx here was sort of OK when each zone was reclaimed separately, as a Normal allocation not passing appropriate classzone_idx (and thus subtracting lowmem reserve from free pages) means that a false COMPACT_PARTIAL (or COMPACT_CONTINUE) could be returned for e.g. DMA zone. It means a premature end of reclaim for this single zone, which is relatively small anyway, so no big deal (and we might avoid useless over-reclaim, when even reclaiming everything wouldn't get us above the lowmem_reserve).
But in node-centric reclaim, such premature "return false" from a DMA zone stops reclaiming the whole node. So I think we should involve the real classzone_idx here.
> + case COMPACT_PARTIAL: > + case COMPACT_CONTINUE: > + return false; > + default: > + /* check next zone */ > + ; > + } > } > + return true; > } >
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