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Date: Thu, 28 Aug 2014 19:35:19 +0100
From: Mel Gorman <mgorman@...e.de>
To: Jiri Slaby <jslaby@...e.cz>
Cc: Linux-Stable <stable@...r.kernel.org>,
LKML <linux-kernel@...r.kernel.org>, Mel Gorman <mgorman@...e.de>
Subject: [PATCH 71/97] mm: page_alloc: use jump labels to avoid checking number_of_cpusets
commit 664eeddeef6539247691197c1ac124d4aa872ab6 upstream.
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@...e.de>
Reviewed-by: Rik van Riel <riel@...hat.com>
Cc: Johannes Weiner <hannes@...xchg.org>
Cc: Vlastimil Babka <vbabka@...e.cz>
Cc: Jan Kara <jack@...e.cz>
Cc: Michal Hocko <mhocko@...e.cz>
Cc: Hugh Dickins <hughd@...gle.com>
Cc: Dave Hansen <dave.hansen@...el.com>
Cc: Theodore Ts'o <tytso@....edu>
Cc: "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
Cc: Oleg Nesterov <oleg@...hat.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Stephen Rothwell <sfr@...b.auug.org.au>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Mel Gorman <mgorman@...e.de>
---
include/linux/cpuset.h | 29 ++++++++++++++++++++++++++---
kernel/cpuset.c | 14 ++++----------
mm/page_alloc.c | 3 ++-
3 files changed, 32 insertions(+), 14 deletions(-)
diff --git a/include/linux/cpuset.h b/include/linux/cpuset.h
index 6f30672..a7ebb89 100644
--- a/include/linux/cpuset.h
+++ b/include/linux/cpuset.h
@@ -12,10 +12,31 @@
#include <linux/cpumask.h>
#include <linux/nodemask.h>
#include <linux/mm.h>
+#include <linux/jump_label.h>
#ifdef CONFIG_CPUSETS
-extern int number_of_cpusets; /* How many cpusets are defined in system? */
+extern struct static_key cpusets_enabled_key;
+static inline bool cpusets_enabled(void)
+{
+ return static_key_false(&cpusets_enabled_key);
+}
+
+static inline int nr_cpusets(void)
+{
+ /* jump label reference count + the top-level cpuset */
+ return static_key_count(&cpusets_enabled_key) + 1;
+}
+
+static inline void cpuset_inc(void)
+{
+ static_key_slow_inc(&cpusets_enabled_key);
+}
+
+static inline void cpuset_dec(void)
+{
+ static_key_slow_dec(&cpusets_enabled_key);
+}
extern int cpuset_init(void);
extern void cpuset_init_smp(void);
@@ -32,13 +53,13 @@ extern int __cpuset_node_allowed_hardwall(int node, gfp_t gfp_mask);
static inline int cpuset_node_allowed_softwall(int node, gfp_t gfp_mask)
{
- return number_of_cpusets <= 1 ||
+ return nr_cpusets() <= 1 ||
__cpuset_node_allowed_softwall(node, gfp_mask);
}
static inline int cpuset_node_allowed_hardwall(int node, gfp_t gfp_mask)
{
- return number_of_cpusets <= 1 ||
+ return nr_cpusets() <= 1 ||
__cpuset_node_allowed_hardwall(node, gfp_mask);
}
@@ -120,6 +141,8 @@ static inline void set_mems_allowed(nodemask_t nodemask)
#else /* !CONFIG_CPUSETS */
+static inline bool cpusets_enabled(void) { return false; }
+
static inline int cpuset_init(void) { return 0; }
static inline void cpuset_init_smp(void) {}
diff --git a/kernel/cpuset.c b/kernel/cpuset.c
index 15ae2b7..c828913 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;
@@ -1986,7 +1981,7 @@ 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;
@@ -2037,7 +2032,7 @@ 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);
@@ -2092,7 +2087,6 @@ int __init cpuset_init(void)
if (!alloc_cpumask_var(&cpus_attach, GFP_KERNEL))
BUG();
- number_of_cpusets = 1;
return 0;
}
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 68e0349..5e0f137 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1920,7 +1920,8 @@ zonelist_scan:
if (IS_ENABLED(CONFIG_NUMA) && zlc_active &&
!zlc_zone_worth_trying(zonelist, z, allowednodes))
continue;
- if ((alloc_flags & ALLOC_CPUSET) &&
+ if (cpusets_enabled() &&
+ (alloc_flags & ALLOC_CPUSET) &&
!cpuset_zone_allowed_softwall(zone, gfp_mask))
continue;
BUILD_BUG_ON(ALLOC_NO_WATERMARKS < NR_WMARK);
--
1.8.4.5
--
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