diff options
| author | akpm@osdl.org <akpm@osdl.org> | 2005-06-21 17:14:35 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-06-21 18:46:13 -0700 |
| commit | b15e0905f2b9964fc7426fecab57445e96021b61 (patch) | |
| tree | bc1b3606cf282f88cd6598de22190eff6708affa /mm/vmscan.c | |
| parent | 39c715b71740c4a78ba4769fb54826929bac03cb (diff) | |
[PATCH] vmscan: notice slab shrinking
Fix a problem identified by Andrea Arcangeli <andrea@suse.de>
kswapd will set a zone into all_unreclaimable state if it sees that we're not
successfully reclaiming LRU pages. But that fails to notice that we're
successfully reclaiming slab obects, so we can set all_unreclaimable too soon.
So change shrink_slab() to return a success indication if it actually
reclaimed some objects, and don't assume that the zone is all_unreclaimable if
that is true. This means that we won't enter all_unreclaimable state if we
are successfully freeing slab objects but we're not yet actually freeing slab
pages, due to internal fragmentation.
(hm, this has a shortcoming. We could be successfully freeing ZONE_NORMAL
slab objects while being really oom on ZONE_DMA. If that happens then kswapd
might burn a lot of CPU. But given that there might be some slab objects in
ZONE_DMA, perhaps that is appropriate.)
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'mm/vmscan.c')
| -rw-r--r-- | mm/vmscan.c | 19 |
1 files changed, 14 insertions, 5 deletions
diff --git a/mm/vmscan.c b/mm/vmscan.c index 269eded9b45..c62cadce042 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -180,17 +180,20 @@ EXPORT_SYMBOL(remove_shrinker); * `lru_pages' represents the number of on-LRU pages in all the zones which * are eligible for the caller's allocation attempt. It is used for balancing * slab reclaim versus page reclaim. + * + * Returns the number of slab objects which we shrunk. */ static int shrink_slab(unsigned long scanned, unsigned int gfp_mask, unsigned long lru_pages) { struct shrinker *shrinker; + int ret = 0; if (scanned == 0) scanned = SWAP_CLUSTER_MAX; if (!down_read_trylock(&shrinker_rwsem)) - return 0; + return 1; /* Assume we'll be able to shrink next time */ list_for_each_entry(shrinker, &shrinker_list, list) { unsigned long long delta; @@ -209,10 +212,14 @@ static int shrink_slab(unsigned long scanned, unsigned int gfp_mask, while (total_scan >= SHRINK_BATCH) { long this_scan = SHRINK_BATCH; int shrink_ret; + int nr_before; + nr_before = (*shrinker->shrinker)(0, gfp_mask); shrink_ret = (*shrinker->shrinker)(this_scan, gfp_mask); if (shrink_ret == -1) break; + if (shrink_ret < nr_before) + ret += nr_before - shrink_ret; mod_page_state(slabs_scanned, this_scan); total_scan -= this_scan; @@ -222,7 +229,7 @@ static int shrink_slab(unsigned long scanned, unsigned int gfp_mask, shrinker->nr += total_scan; } up_read(&shrinker_rwsem); - return 0; + return ret; } /* Called without lock on whether page is mapped, so answer is unstable */ @@ -1079,6 +1086,7 @@ scan: */ for (i = 0; i <= end_zone; i++) { struct zone *zone = pgdat->node_zones + i; + int nr_slab; if (zone->present_pages == 0) continue; @@ -1100,14 +1108,15 @@ scan: sc.swap_cluster_max = nr_pages? nr_pages : SWAP_CLUSTER_MAX; shrink_zone(zone, &sc); reclaim_state->reclaimed_slab = 0; - shrink_slab(sc.nr_scanned, GFP_KERNEL, lru_pages); + nr_slab = shrink_slab(sc.nr_scanned, GFP_KERNEL, + lru_pages); sc.nr_reclaimed += reclaim_state->reclaimed_slab; total_reclaimed += sc.nr_reclaimed; total_scanned += sc.nr_scanned; if (zone->all_unreclaimable) continue; - if (zone->pages_scanned >= (zone->nr_active + - zone->nr_inactive) * 4) + if (nr_slab == 0 && zone->pages_scanned >= + (zone->nr_active + zone->nr_inactive) * 4) zone->all_unreclaimable = 1; /* * If we've done a decent amount of scanning and |