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authorLinus Torvalds <torvalds@linux-foundation.org>2013-07-02 19:53:30 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2013-07-02 19:53:30 -0700
commitf317ff9eed763e99bd226a447f93d42509434f43 (patch)
treed77edfcdb1e7c32c30327f50dce04bcff8ec1531 /kernel/power
parent13cc56013842a847a0f6ff805d9ed9181e753ef8 (diff)
parenta85f1a41f020bc2c97611060bcfae6f48a1db28d (diff)
Merge branch 'for-3.11' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq
Pull workqueue changes from Tejun Heo: "Surprisingly, Lai and I didn't break too many things implementing custom pools and stuff last time around and there aren't any follow-up changes necessary at this point. The only change in this pull request is Viresh's patches to make some per-cpu workqueues to behave as unbound workqueues dependent on a boot param whose default can be configured via a config option. This leads to higher processing overhead / lower bandwidth as more work items are bounced across CPUs; however, it can lead to noticeable powersave in certain configurations - ~10% w/ idlish constant workload on a big.LITTLE configuration according to Viresh. This is because per-cpu workqueues interfere with how the scheduler perceives whether or not each CPU is idle by forcing pinned tasks on them, which makes the scheduler's power-aware scheduling decisions less effective. Its effectiveness is likely less pronounced on homogenous configurations and this type of optimization can probably be made automatic; however, the changes are pretty minimal and the affected workqueues are clearly marked, so it's an easy gain for some configurations for the time being with pretty unintrusive changes." * 'for-3.11' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq: fbcon: queue work on power efficient wq block: queue work on power efficient wq PHYLIB: queue work on system_power_efficient_wq workqueue: Add system wide power_efficient workqueues workqueues: Introduce new flag WQ_POWER_EFFICIENT for power oriented workqueues
Diffstat (limited to 'kernel/power')
-rw-r--r--kernel/power/Kconfig20
1 files changed, 20 insertions, 0 deletions
diff --git a/kernel/power/Kconfig b/kernel/power/Kconfig
index 9c39de095ba..d444c4e834f 100644
--- a/kernel/power/Kconfig
+++ b/kernel/power/Kconfig
@@ -262,6 +262,26 @@ config PM_GENERIC_DOMAINS
bool
depends on PM
+config WQ_POWER_EFFICIENT_DEFAULT
+ bool "Enable workqueue power-efficient mode by default"
+ depends on PM
+ default n
+ help
+ Per-cpu workqueues are generally preferred because they show
+ better performance thanks to cache locality; unfortunately,
+ per-cpu workqueues tend to be more power hungry than unbound
+ workqueues.
+
+ Enabling workqueue.power_efficient kernel parameter makes the
+ per-cpu workqueues which were observed to contribute
+ significantly to power consumption unbound, leading to measurably
+ lower power usage at the cost of small performance overhead.
+
+ This config option determines whether workqueue.power_efficient
+ is enabled by default.
+
+ If in doubt, say N.
+
config PM_GENERIC_DOMAINS_SLEEP
def_bool y
depends on PM_SLEEP && PM_GENERIC_DOMAINS