Messages in this thread | ![/](/images/icornerl.gif) | | From | KOSAKI Motohiro <> | Subject | Re: Free memory never fully used, swapping | Date | Fri, 26 Nov 2010 11:31:42 +0900 (JST) |
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> record the order seems not sufficient. in balance_pgdat(), the for look > exit only when: > priority <0 or sc.nr_reclaimed >= SWAP_CLUSTER_MAX. > but we do if (sc.nr_reclaimed < SWAP_CLUSTER_MAX) > order = sc.order = 0; > this means before we set order to 0, we already reclaimed a lot of > pages, so I thought we need set order to 0 earlier before there are > enough free pages. below is a debug patch. > > > diff --git a/mm/vmscan.c b/mm/vmscan.c > index d31d7ce..ee5d2ed 100644 > --- a/mm/vmscan.c > +++ b/mm/vmscan.c > @@ -2117,6 +2117,26 @@ unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *mem_cont, > } > #endif > > +static int all_zone_enough_free_pages(pg_data_t *pgdat) > +{ > + int i; > + > + for (i = 0; i < pgdat->nr_zones; i++) { > + struct zone *zone = pgdat->node_zones + i; > + > + if (!populated_zone(zone)) > + continue; > + > + if (zone->all_unreclaimable) > + continue; > + > + if (!zone_watermark_ok(zone, 0, high_wmark_pages(zone) * 8, > + 0, 0)) > + return 0; > + } > + return 1; > +} > + > /* is kswapd sleeping prematurely? */ > static int sleeping_prematurely(pg_data_t *pgdat, int order, long remaining) > { > @@ -2355,7 +2375,8 @@ out: > * back to sleep. High-order users can still perform direct > * reclaim if they wish. > */ > - if (sc.nr_reclaimed < SWAP_CLUSTER_MAX) > + if (sc.nr_reclaimed < SWAP_CLUSTER_MAX || > + (order > 0 && all_zone_enough_free_pages(pgdat))) > order = sc.order = 0;
Ummm. this doesn't work. this place is processed every 32 pages reclaimed. (see below code and comment). Theresore your patch break high order reclaim logic.
/* * We do this so kswapd doesn't build up large priorities for * example when it is freeing in parallel with allocators. It * matches the direct reclaim path behaviour in terms of impact * on zone->*_priority. */ if (sc.nr_reclaimed >= SWAP_CLUSTER_MAX) break;
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