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authorMel Gorman <mgorman@suse.de>2014-06-04 16:10:08 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2014-06-04 16:54:08 -0700
commit664eeddeef6539247691197c1ac124d4aa872ab6 (patch)
tree568fa77ea4d8b525efeec73e398951b6089374f8 /kernel/cpuset.c
parentea5e9539abf1258f23e725cb9cb25aa74efa29eb (diff)
mm: page_alloc: use jump labels to avoid checking number_of_cpusets
If cpusets are not in use then we still check a global variable on every page allocation. Use jump labels to avoid the overhead. Signed-off-by: Mel Gorman <mgorman@suse.de> Reviewed-by: Rik van Riel <riel@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Jan Kara <jack@suse.cz> Cc: Michal Hocko <mhocko@suse.cz> Cc: Hugh Dickins <hughd@google.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Theodore Ts'o <tytso@mit.edu> Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel/cpuset.c')
-rw-r--r--kernel/cpuset.c14
1 files changed, 4 insertions, 10 deletions
diff --git a/kernel/cpuset.c b/kernel/cpuset.c
index 3d54c418bd06..130017843899 100644
--- a/kernel/cpuset.c
+++ b/kernel/cpuset.c
@@ -61,12 +61,7 @@
#include <linux/cgroup.h>
#include <linux/wait.h>
-/*
- * Tracks how many cpusets are currently defined in system.
- * When there is only one cpuset (the root cpuset) we can
- * short circuit some hooks.
- */
-int number_of_cpusets __read_mostly;
+struct static_key cpusets_enabled_key __read_mostly = STATIC_KEY_INIT_FALSE;
/* See "Frequency meter" comments, below. */
@@ -611,7 +606,7 @@ static int generate_sched_domains(cpumask_var_t **domains,
goto done;
}
- csa = kmalloc(number_of_cpusets * sizeof(cp), GFP_KERNEL);
+ csa = kmalloc(nr_cpusets() * sizeof(cp), GFP_KERNEL);
if (!csa)
goto done;
csn = 0;
@@ -1888,7 +1883,7 @@ static int cpuset_css_online(struct cgroup_subsys_state *css)
if (is_spread_slab(parent))
set_bit(CS_SPREAD_SLAB, &cs->flags);
- number_of_cpusets++;
+ cpuset_inc();
if (!test_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags))
goto out_unlock;
@@ -1939,7 +1934,7 @@ static void cpuset_css_offline(struct cgroup_subsys_state *css)
if (is_sched_load_balance(cs))
update_flag(CS_SCHED_LOAD_BALANCE, cs, 0);
- number_of_cpusets--;
+ cpuset_dec();
clear_bit(CS_ONLINE, &cs->flags);
mutex_unlock(&cpuset_mutex);
@@ -1992,7 +1987,6 @@ int __init cpuset_init(void)
if (!alloc_cpumask_var(&cpus_attach, GFP_KERNEL))
BUG();
- number_of_cpusets = 1;
return 0;
}