From: Wu Fengguang <fengguang.wu@intel.com>
Date: Wed, 25 May 2011 00:12:28 +0000 (-0700)
Subject: readahead: return early when readahead is disabled
X-Git-Tag: v3.0-rc1~242
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=275b12bf5486f6f531111fd3d7dbbf01df427cfe;p=pandora-kernel.git

readahead: return early when readahead is disabled

Reduce readahead overheads by returning early in do_sync_mmap_readahead().

tmpfs has ra_pages=0 and it can page fault really fast (not constraint by
IO if not swapping).

Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
Tested-by: Tim Chen <tim.c.chen@intel.com>
Reported-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

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