From: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx> Subject: mm: page_alloc: cache the last node whose dirty limit is reached If a page is about to be dirtied then the page allocator attempts to limit the total number of dirty pages that exists in any given zone. The call to node_dirty_ok is expensive so this patch records if the last pgdat examined hit the dirty limits. In some cases, this reduces the number of calls to node_dirty_ok(). Link: http://lkml.kernel.org/r/1467970510-21195-31-git-send-email-mgorman@xxxxxxxxxxxxxxxxxxx Signed-off-by: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx> Acked-by: Vlastimil Babka <vbabka@xxxxxxx> Cc: Hillf Danton <hillf.zj@xxxxxxxxxxxxxxx> Acked-by: Johannes Weiner <hannes@xxxxxxxxxxx> Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx> Cc: Michal Hocko <mhocko@xxxxxxxxxx> Cc: Minchan Kim <minchan@xxxxxxxxxx> Cc: Rik van Riel <riel@xxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/page_alloc.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-) diff -puN mm/page_alloc.c~mm-page_alloc-cache-the-last-node-whose-dirty-limit-is-reached mm/page_alloc.c --- a/mm/page_alloc.c~mm-page_alloc-cache-the-last-node-whose-dirty-limit-is-reached +++ a/mm/page_alloc.c @@ -2848,6 +2848,8 @@ get_page_from_freelist(gfp_t gfp_mask, u { struct zoneref *z = ac->preferred_zoneref; struct zone *zone; + struct pglist_data *last_pgdat_dirty_limit = NULL; + /* * Scan zonelist, looking for a zone with enough free. * See also __cpuset_node_allowed() comment in kernel/cpuset.c. @@ -2880,8 +2882,15 @@ get_page_from_freelist(gfp_t gfp_mask, u * will require awareness of nodes in the * dirty-throttling and the flusher threads. */ - if (ac->spread_dirty_pages && !node_dirty_ok(zone->zone_pgdat)) - continue; + if (ac->spread_dirty_pages) { + if (last_pgdat_dirty_limit == zone->zone_pgdat) + continue; + + if (!node_dirty_ok(zone->zone_pgdat)) { + last_pgdat_dirty_limit = zone->zone_pgdat; + continue; + } + } mark = zone->watermark[alloc_flags & ALLOC_WMARK_MASK]; if (!zone_watermark_fast(zone, order, mark, _ -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
