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From: Aaron Lu <aaron.lu@intel.com>
To: linux-mm@kvack.org, linux-kernel@vger.kernel.org
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Huang Ying <ying.huang@intel.com>,
	Dave Hansen <dave.hansen@intel.com>,
	Kemi Wang <kemi.wang@intel.com>,
	Tim Chen <tim.c.chen@linux.intel.com>,
	Andi Kleen <ak@linux.intel.com>, Michal Hocko <mhocko@suse.com>,
	Vlastimil Babka <vbabka@suse.cz>,
	Mel Gorman <mgorman@techsingularity.net>,
	Matthew Wilcox <willy@infradead.org>
Subject: [PATCH v3 1/3] mm/free_pcppages_bulk: update pcp->count inside
Date: Mon, 26 Feb 2018 21:53:44 +0800	[thread overview]
Message-ID: <20180226135346.7208-2-aaron.lu@intel.com> (raw)
In-Reply-To: <20180226135346.7208-1-aaron.lu@intel.com>

Matthew Wilcox found that all callers of free_pcppages_bulk() currently
update pcp->count immediately after so it's natural to do it inside
free_pcppages_bulk().

No functionality or performance change is expected from this patch.

Suggested-by: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Aaron Lu <aaron.lu@intel.com>
---
 mm/page_alloc.c | 10 +++-------
 1 file changed, 3 insertions(+), 7 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index cb416723538f..3154859cccd6 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1117,6 +1117,7 @@ static void free_pcppages_bulk(struct zone *zone, int count,
 	int batch_free = 0;
 	bool isolated_pageblocks;
 
+	pcp->count -= count;
 	spin_lock(&zone->lock);
 	isolated_pageblocks = has_isolate_pageblock(zone);
 
@@ -2416,10 +2417,8 @@ void drain_zone_pages(struct zone *zone, struct per_cpu_pages *pcp)
 	local_irq_save(flags);
 	batch = READ_ONCE(pcp->batch);
 	to_drain = min(pcp->count, batch);
-	if (to_drain > 0) {
+	if (to_drain > 0)
 		free_pcppages_bulk(zone, to_drain, pcp);
-		pcp->count -= to_drain;
-	}
 	local_irq_restore(flags);
 }
 #endif
@@ -2441,10 +2440,8 @@ static void drain_pages_zone(unsigned int cpu, struct zone *zone)
 	pset = per_cpu_ptr(zone->pageset, cpu);
 
 	pcp = &pset->pcp;
-	if (pcp->count) {
+	if (pcp->count)
 		free_pcppages_bulk(zone, pcp->count, pcp);
-		pcp->count = 0;
-	}
 	local_irq_restore(flags);
 }
 
@@ -2668,7 +2665,6 @@ static void free_unref_page_commit(struct page *page, unsigned long pfn)
 	if (pcp->count >= pcp->high) {
 		unsigned long batch = READ_ONCE(pcp->batch);
 		free_pcppages_bulk(zone, batch, pcp);
-		pcp->count -= batch;
 	}
 }
 
-- 
2.14.3

  reply	other threads:[~2018-02-26 13:52 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-02-26 13:53 [PATCH v3 0/3] mm: improve zone->lock scalability Aaron Lu
2018-02-26 13:53 ` Aaron Lu [this message]
2018-02-26 21:48   ` [PATCH v3 1/3] mm/free_pcppages_bulk: update pcp->count inside David Rientjes
2018-02-27  1:56     ` Aaron Lu
2018-02-27  3:12       ` Aaron Lu
2018-02-26 13:53 ` [PATCH v3 2/3] mm/free_pcppages_bulk: do not hold lock when picking pages to free Aaron Lu
2018-02-26 21:53   ` David Rientjes
2018-02-27  2:00     ` Aaron Lu
2018-02-27  3:17       ` Aaron Lu
2018-02-26 13:53 ` [PATCH v3 3/3] mm/free_pcppages_bulk: prefetch buddy while not holding lock Aaron Lu

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