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Commit e0c23279c9f800c403f37511484d9014ac83adec

Authored by Mel Gorman
Committed by Linus Torvalds
1 parent e0887c19b2
Exists in master and in 6 other branches imx_3.10.17_1.0.1_ga, imx_3.10.53_1.1.0_ga, imx_3.14.28_1.0.0_ga, smarc-imx_3.10.53_1.1.0_ga, smarc-imx_3.14.28_1.0.0_ga, smarc-l5.0.0_1.0.0-ga

vmscan: abort reclaim/compaction if compaction can proceed 

If compaction can proceed, shrink_zones() stops doing any work but its
callers still call shrink_slab() which raises the priority and potentially
sleeps.  This is unnecessary and wasteful so this patch aborts direct
reclaim/compaction entirely if compaction can proceed.

Signed-off-by: Mel Gorman <mgorman@suse.de>
Acked-by: Rik van Riel <riel@redhat.com>
Reviewed-by: Minchan Kim <minchan.kim@gmail.com>
Acked-by: Johannes Weiner <jweiner@redhat.com>
Cc: Josh Boyer <jwboyer@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Showing 1 changed file with 21 additions and 11 deletions Side-by-side Diff

... ... @@ -2103,14 +2103,19 @@
2103 2103 *
2104 2104 * If a zone is deemed to be full of pinned pages then just give it a light
2105 2105 * scan then give up on it.
  2106 + *
  2107 + * This function returns true if a zone is being reclaimed for a costly
  2108 + * high-order allocation and compaction is either ready to begin or deferred.
  2109 + * This indicates to the caller that it should retry the allocation or fail.
2106 2110 */
2107   -static void shrink_zones(int priority, struct zonelist *zonelist,
  2111 +static bool shrink_zones(int priority, struct zonelist *zonelist,
2108 2112 struct scan_control *sc)
2109 2113 {
2110 2114 struct zoneref *z;
2111 2115 struct zone *zone;
2112 2116 unsigned long nr_soft_reclaimed;
2113 2117 unsigned long nr_soft_scanned;
  2118 + bool should_abort_reclaim = false;
2114 2119  
2115 2120 for_each_zone_zonelist_nodemask(zone, z, zonelist,
2116 2121 gfp_zone(sc->gfp_mask), sc->nodemask) {
2117 2122  
2118 2123  
... ... @@ -2127,19 +2132,20 @@
2127 2132 continue; /* Let kswapd poll it */
2128 2133 if (COMPACTION_BUILD) {
2129 2134 /*
2130   - * If we already have plenty of memory
2131   - * free for compaction, don't free any
2132   - * more. Even though compaction is
2133   - * invoked for any non-zero order,
2134   - * only frequent costly order
2135   - * reclamation is disruptive enough to
2136   - * become a noticable problem, like
2137   - * transparent huge page allocations.
  2135 + * If we already have plenty of memory free for
  2136 + * compaction in this zone, don't free any more.
  2137 + * Even though compaction is invoked for any
  2138 + * non-zero order, only frequent costly order
  2139 + * reclamation is disruptive enough to become a
  2140 + * noticable problem, like transparent huge page
  2141 + * allocations.
2138 2142 */
2139 2143 if (sc->order > PAGE_ALLOC_COSTLY_ORDER &&
2140 2144 (compaction_suitable(zone, sc->order) ||
2141   - compaction_deferred(zone)))
  2145 + compaction_deferred(zone))) {
  2146 + should_abort_reclaim = true;
2142 2147 continue;
  2148 + }
2143 2149 }
2144 2150 /*
2145 2151 * This steals pages from memory cgroups over softlimit
... ... @@ -2158,6 +2164,8 @@
2158 2164  
2159 2165 shrink_zone(priority, zone, sc);
2160 2166 }
  2167 +
  2168 + return should_abort_reclaim;
2161 2169 }
2162 2170  
2163 2171 static bool zone_reclaimable(struct zone *zone)
... ... @@ -2222,7 +2230,9 @@
2222 2230 sc->nr_scanned = 0;
2223 2231 if (!priority)
2224 2232 disable_swap_token(sc->mem_cgroup);
2225   - shrink_zones(priority, zonelist, sc);
  2233 + if (shrink_zones(priority, zonelist, sc))
  2234 + break;
  2235 +
2226 2236 /*
2227 2237 * Don't shrink slabs when reclaiming memory from
2228 2238 * over limit cgroups