lkml.org 
[lkml]   [2014]   [May]   [1]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 03/17] mm: page_alloc: Use jump labels to avoid checking number_of_cpusets
Date
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>
---
include/linux/cpuset.h | 31 +++++++++++++++++++++++++++++++
kernel/cpuset.c | 8 ++++++--
mm/page_alloc.c | 3 ++-
3 files changed, 39 insertions(+), 3 deletions(-)

diff --git a/include/linux/cpuset.h b/include/linux/cpuset.h
index b19d3dc..2b89e07 100644
--- a/include/linux/cpuset.h
+++ b/include/linux/cpuset.h
@@ -17,6 +17,35 @@

extern int number_of_cpusets; /* How many cpusets are defined in system? */

+#ifdef HAVE_JUMP_LABEL
+extern struct static_key cpusets_enabled_key;
+static inline bool cpusets_enabled(void)
+{
+ return static_key_false(&cpusets_enabled_key);
+}
+#else
+static inline bool cpusets_enabled(void)
+{
+ return number_of_cpusets > 1;
+}
+#endif
+
+static inline void cpuset_inc(void)
+{
+ number_of_cpusets++;
+#ifdef HAVE_JUMP_LABEL
+ static_key_slow_inc(&cpusets_enabled_key);
+#endif
+}
+
+static inline void cpuset_dec(void)
+{
+ number_of_cpusets--;
+#ifdef HAVE_JUMP_LABEL
+ static_key_slow_dec(&cpusets_enabled_key);
+#endif
+}
+
extern int cpuset_init(void);
extern void cpuset_init_smp(void);
extern void cpuset_update_active_cpus(bool cpu_online);
@@ -124,6 +153,8 @@ 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 3d54c41..34ada52 100644
--- a/kernel/cpuset.c
+++ b/kernel/cpuset.c
@@ -68,6 +68,10 @@
*/
int number_of_cpusets __read_mostly;

+#ifdef HAVE_JUMP_LABEL
+struct static_key cpusets_enabled_key = STATIC_KEY_INIT_FALSE;
+#endif
+
/* See "Frequency meter" comments, below. */

struct fmeter {
@@ -1888,7 +1892,7 @@ 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 +1943,7 @@ 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);
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 5c559e3..cb12b9a 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1930,7 +1930,8 @@ 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


\
 
 \ /
  Last update: 2014-05-01 11:41    [W:0.284 / U:0.368 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site