On Sun 17-03-13 13:04:14, Mel Gorman wrote: > If kswaps fails to make progress but continues to shrink slab then it'll > either discard all of slab or consume CPU uselessly scanning shrinkers. > This patch causes kswapd to only call the shrinkers once per priority. > > Signed-off-by: Mel Gorman <[email protected]>
OK, looks good. Reviewed-by: Michal Hocko <[email protected]> > --- > mm/vmscan.c | 28 +++++++++++++++++++++------- > 1 file changed, 21 insertions(+), 7 deletions(-) > > diff --git a/mm/vmscan.c b/mm/vmscan.c > index 7d5a932..84375b2 100644 > --- a/mm/vmscan.c > +++ b/mm/vmscan.c > @@ -2661,9 +2661,10 @@ static bool prepare_kswapd_sleep(pg_data_t *pgdat, int > order, long remaining, > */ > static bool kswapd_shrink_zone(struct zone *zone, > struct scan_control *sc, > - unsigned long lru_pages) > + unsigned long lru_pages, > + bool shrinking_slab) > { > - unsigned long nr_slab; > + unsigned long nr_slab = 0; > struct reclaim_state *reclaim_state = current->reclaim_state; > struct shrink_control shrink = { > .gfp_mask = sc->gfp_mask, > @@ -2673,9 +2674,15 @@ static bool kswapd_shrink_zone(struct zone *zone, > sc->nr_to_reclaim = max(SWAP_CLUSTER_MAX, high_wmark_pages(zone)); > shrink_zone(zone, sc); > > - reclaim_state->reclaimed_slab = 0; > - nr_slab = shrink_slab(&shrink, sc->nr_scanned, lru_pages); > - sc->nr_reclaimed += reclaim_state->reclaimed_slab; > + /* > + * Slabs are shrunk for each zone once per priority or if the zone > + * being balanced is otherwise unreclaimable > + */ > + if (shrinking_slab || !zone_reclaimable(zone)) { > + reclaim_state->reclaimed_slab = 0; > + nr_slab = shrink_slab(&shrink, sc->nr_scanned, lru_pages); > + sc->nr_reclaimed += reclaim_state->reclaimed_slab; > + } > > if (nr_slab == 0 && !zone_reclaimable(zone)) > zone->all_unreclaimable = 1; > @@ -2713,6 +2720,7 @@ static unsigned long balance_pgdat(pg_data_t *pgdat, > int order, > int end_zone = 0; /* Inclusive. 0 = ZONE_DMA */ > unsigned long nr_soft_reclaimed; > unsigned long nr_soft_scanned; > + bool shrinking_slab = true; > struct scan_control sc = { > .gfp_mask = GFP_KERNEL, > .priority = DEF_PRIORITY, > @@ -2861,7 +2869,8 @@ static unsigned long balance_pgdat(pg_data_t *pgdat, > int order, > * already being scanned that that high > * watermark would be met at 100% efficiency. > */ > - if (kswapd_shrink_zone(zone, &sc, lru_pages)) > + if (kswapd_shrink_zone(zone, &sc, > + lru_pages, shrinking_slab)) > raise_priority = false; > > nr_to_reclaim += sc.nr_to_reclaim; > @@ -2900,6 +2909,9 @@ static unsigned long balance_pgdat(pg_data_t *pgdat, > int order, > pfmemalloc_watermark_ok(pgdat)) > wake_up(&pgdat->pfmemalloc_wait); > > + /* Only shrink slab once per priority */ > + shrinking_slab = false; > + > /* > * Fragmentation may mean that the system cannot be rebalanced > * for high-order allocations in all zones. If twice the > @@ -2925,8 +2937,10 @@ static unsigned long balance_pgdat(pg_data_t *pgdat, > int order, > * Raise priority if scanning rate is too low or there was no > * progress in reclaiming pages > */ > - if (raise_priority || !this_reclaimed) > + if (raise_priority || !this_reclaimed) { > sc.priority--; > + shrinking_slab = true; > + } > } while (sc.priority >= 1 && > !pgdat_balanced(pgdat, order, *classzone_idx)); > > -- > 1.8.1.4 > -- Michal Hocko SUSE Labs -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
