mm, mempolicy: remove per-process flag
authorDavid Rientjes <rientjes@google.com>
Mon, 7 Apr 2014 22:37:30 +0000 (15:37 -0700)
committerLinus Torvalds <torvalds@linux-foundation.org>
Mon, 7 Apr 2014 23:35:54 +0000 (16:35 -0700)
commitf0432d159601f96839f514f286eaa5b75c4112dc
tree654f94de69e9b7465480172b09e6838f08e81989
parent2a389610a7331d22344698f23ef2e8c55b2cde7b
mm, mempolicy: remove per-process flag

PF_MEMPOLICY is an unnecessary optimization for CONFIG_SLAB users.
There's no significant performance degradation to checking
current->mempolicy rather than current->flags & PF_MEMPOLICY in the
allocation path, especially since this is considered unlikely().

Running TCP_RR with netperf-2.4.5 through localhost on 16 cpu machine with
64GB of memory and without a mempolicy:

threads before after
16 1249409 1244487
32 1281786 1246783
48 1239175 1239138
64 1244642 1241841
80 1244346 1248918
96 1266436 1254316
112 1307398 1312135
128 1327607 1326502

Per-process flags are a scarce resource so we should free them up whenever
possible and make them available.  We'll be using it shortly for memcg oom
reserves.

Signed-off-by: David Rientjes <rientjes@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Christoph Lameter <cl@linux-foundation.org>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Jianguo Wu <wujianguo@huawei.com>
Cc: Tim Hockin <thockin@google.com>
Cc: Christoph Lameter <cl@linux.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
include/linux/mempolicy.h
include/linux/sched.h
kernel/fork.c
mm/mempolicy.c
mm/slab.c