linux-kernel - Re: [PATCH 3/3] mm: page allocator: Drain per-cpu lists after direct reclaim allocation fails

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Message-Id: <20100908163956.C930.A69D9226@jp.fujitsu.com>
Date:	Wed,  8 Sep 2010 16:43:03 +0900 (JST)
From:	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
To:	Mel Gorman <mel@....ul.ie>
Cc:	kosaki.motohiro@...fujitsu.com,
	Andrew Morton <akpm@...ux-foundation.org>,
	Linux Kernel List <linux-kernel@...r.kernel.org>,
	linux-mm@...ck.org, Rik van Riel <riel@...hat.com>,
	Johannes Weiner <hannes@...xchg.org>,
	Minchan Kim <minchan.kim@...il.com>,
	Christoph Lameter <cl@...ux-foundation.org>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
Subject: Re: [PATCH 3/3] mm: page allocator: Drain per-cpu lists after direct reclaim allocation fails

> +	/*
> +	 * If an allocation failed after direct reclaim, it could be because
> +	 * pages are pinned on the per-cpu lists. Drain them and try again
> +	 */
> +	if (!page && !drained) {
> +		drain_all_pages();
> +		drained = true;
> +		goto retry;
> +	}

nit: when slub, get_page_from_freelist() failure is frequently happen
than slab because slub try to allocate high order page at first.
So, I guess we have to avoid drain_all_pages() if __GFP_NORETRY is passed.




>From 9209ceb1d48446b031576ba9360036ddabc1a0e5 Mon Sep 17 00:00:00 2001
From: KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
Date: Fri, 10 Sep 2010 03:29:05 +0900
Subject: [PATCH] mm: don't call drain_all_pages() when __GFP_NORETRY

SLUB try to allocate high order pages at first. therefore page allocator
eventually call drain_all_pages() frequently. We don't hope IPI storm.
Thus, we don't call drain_all_pages() when caller passed __GFP_NORETRY.

Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
---
 mm/page_alloc.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 8587c10..b9eafb1 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1878,7 +1878,7 @@ retry:
 	 * If an allocation failed after direct reclaim, it could be because
 	 * pages are pinned on the per-cpu lists. Drain them and try again
 	 */
-	if (!page && !drained) {
+	if (!page && !drained && !(gfp_mask & __GFP_NORETRY)) {
 		drain_all_pages();
 		drained = true;
 		goto retry;
-- 
1.6.5.2



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