__alloc_pages_direct_compact has many arguments so invoking it is very costly.
And in almost invoking case, order is 0, so return immediately.
Let's not invoke it when order 0
Signed-off-by: Joonsoo Kim <js1...@gmail.com>
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 6092f33..f4039aa 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -2056,7 +2056,10 @@ out:
}
#ifdef CONFIG_COMPACTION
-/* Try memory compaction for high-order allocations before reclaim */
+/*
+ * Try memory compaction for high-order allocations before reclaim
+ * Must be called with order > 0
+ */
static struct page *
__alloc_pages_direct_compact(gfp_t gfp_mask, unsigned int order,
struct zonelist *zonelist, enum zone_type high_zoneidx,
@@ -2067,8 +2070,7 @@ __alloc_pages_direct_compact(gfp_t gfp_mask, unsigned int
order,
{
struct page *page;
- if (!order)
- return NULL;
+ BUG_ON(!order);
if (compaction_deferred(preferred_zone, order)) {
*deferred_compaction = true;
@@ -2363,15 +2365,17 @@ rebalance:
* Try direct compaction. The first pass is asynchronous. Subsequent
* attempts after direct reclaim are synchronous
*/
- page = __alloc_pages_direct_compact(gfp_mask, order,
- zonelist, high_zoneidx,
- nodemask,
- alloc_flags, preferred_zone,
- migratetype, sync_migration,
- &deferred_compaction,
- &did_some_progress);
- if (page)
- goto got_pg;
+ if (unlikely(order)) {
+ page = __alloc_pages_direct_compact(gfp_mask, order,
+ zonelist, high_zoneidx,
+ nodemask,
+ alloc_flags, preferred_zone,
+ migratetype, sync_migration,
+ &deferred_compaction,
+ &did_some_progress);
+ if (page)
+ goto got_pg;
+ }
sync_migration = true;
/*
@@ -2446,15 +2450,17 @@ rebalance:
* direct reclaim and reclaim/compaction depends on compaction
* being called after reclaim so call directly if necessary
*/
- page = __alloc_pages_direct_compact(gfp_mask, order,
- zonelist, high_zoneidx,
- nodemask,
- alloc_flags, preferred_zone,
- migratetype, sync_migration,
- &deferred_compaction,
- &did_some_progress);
- if (page)
- goto got_pg;
+ if (unlikely(order)) {
+ page = __alloc_pages_direct_compact(gfp_mask, order,
+ zonelist, high_zoneidx,
+ nodemask,
+ alloc_flags, preferred_zone,
+ migratetype, sync_migration,
+ &deferred_compaction,
+ &did_some_progress);
+ if (page)
+ goto got_pg;
+ }
}
nopage:
--
1.7.9.5
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