linux-kernel - [PATCH] mm: don't set __GFP

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Date:	Fri, 2 Mar 2012 14:10:35 +0800
From:	Fengguang Wu <fengguang.wu@...el.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Johannes Weiner <hannes@...xchg.org>, Jan Kara <jack@...e.cz>,
	Greg Thelen <gthelen@...gle.com>,
	Ying Han <yinghan@...gle.com>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
	Rik van Riel <riel@...hat.com>, Mel Gorman <mgorman@...e.de>,
	Minchan Kim <minchan.kim@...il.com>,
	Linux Memory Management List <linux-mm@...ck.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: [PATCH] mm: don't set __GFP_WRITE on ramfs/sysfs writes

There is not much of a point in skipping zones during allocation based
on the dirty usage which they'll never contribute to. And we'd like to
avoid page reclaim waits when writing to ramfs/sysfs etc.

Acked-by: Johannes Weiner <hannes@...xchg.org>
Signed-off-by: Fengguang Wu <fengguang.wu@...el.com>
---
 mm/filemap.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

--- linux.orig/mm/filemap.c	2012-03-02 14:06:47.000000000 +0800
+++ linux/mm/filemap.c	2012-03-02 14:07:21.325766507 +0800
@@ -2341,7 +2341,9 @@ struct page *grab_cache_page_write_begin
 	struct page *page;
 	gfp_t gfp_notmask = 0;
 
-	gfp_mask = mapping_gfp_mask(mapping) | __GFP_WRITE;
+	gfp_mask = mapping_gfp_mask(mapping);
+	if (mapping_cap_account_dirty(mapping))
+		gfp_mask |= __GFP_WRITE;
 	if (flags & AOP_FLAG_NOFS)
 		gfp_notmask = __GFP_FS;
 repeat:
--
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