linux-kernel - [RFC v3 PATCH 5/5] mm/can_skip_merge(): make it more aggressive to attempt cluster alloc/free

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Date:   Wed,  9 May 2018 16:54:50 +0800
From:   Aaron Lu <aaron.lu@...el.com>
To:     linux-mm@...ck.org, linux-kernel@...r.kernel.org
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Huang Ying <ying.huang@...el.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Kemi Wang <kemi.wang@...el.com>,
        Tim Chen <tim.c.chen@...ux.intel.com>,
        Andi Kleen <ak@...ux.intel.com>,
        Michal Hocko <mhocko@...e.com>,
        Vlastimil Babka <vbabka@...e.cz>,
        Mel Gorman <mgorman@...hsingularity.net>,
        Matthew Wilcox <willy@...radead.org>,
        Daniel Jordan <daniel.m.jordan@...cle.com>,
        Tariq Toukan <tariqt@...lanox.com>
Subject: [RFC v3 PATCH 5/5] mm/can_skip_merge(): make it more aggressive to attempt cluster alloc/free

After system runs a long time, it's easy for a zone to have no
suitable high order page available and that will stop cluster alloc
and free in current implementation due to compact_considered > 0.

To make it favour order0 alloc/free, relax the condition to only
disallow cluster alloc/free when problem would occur, e.g. when
compaction is in progress.

Signed-off-by: Aaron Lu <aaron.lu@...el.com>
---
 mm/internal.h | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/mm/internal.h b/mm/internal.h
index e3f209f8fb39..521aa4d8f3c1 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -552,10 +552,6 @@ void try_to_merge_page(struct page *page);
 #ifdef CONFIG_COMPACTION
 static inline bool can_skip_merge(struct zone *zone, int order)
 {
-	/* Compaction has failed in this zone, we shouldn't skip merging */
-	if (zone->compact_considered)
-		return false;
-
 	/* Only consider no_merge for order 0 pages */
 	if (order)
 		return false;
-- 
2.14.3