commit 275b12bf5486f6f531111fd3d7dbbf01df427cfe
author Wu Fengguang <fengguang.wu@intel.com> Tue May 24 17:12:28 2011 -0700
committer Linus Torvalds <torvalds@linux-foundation.org> Wed May 25 08:39:26 2011 -0700
tree ebed0109eaa3e4a015bc1653f4d933f2e84c794f
parent 1495f230fa7750479c79e3656286b9183d662077

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>