Revert "workqueues: Introduce new flag WQ_POWER_EFFICIENT for power oriented workqueues"tracking-big-LITTLE-MP-master-llct-20130715.0tracking-big-LITTLE-MP-master-llct-20130708.0tracking-big-LITTLE-MP-master-llct-20130701.0tracking-big-LITTLE-MP-master-llct-20130626.0big-LITTLE-MP-master-v18

This reverts commit cee22a15052faa817e3ec8985a28154d3fabc7aa.

4 files changed, 0 insertions, 75 deletions

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 09382f35d583..d1179e6eb8af 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -3329,21 +3329,6 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
 			that this also can be controlled per-workqueue for
 			workqueues visible under /sys/bus/workqueue/.
 
-	workqueue.power_efficient
-			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 this 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.
-
-			The default value of this parameter is determined by
-			the config option CONFIG_WQ_POWER_EFFICIENT_DEFAULT.
-
 	x2apic_phys	[X86-64,APIC] Use x2apic physical mode instead of
 			default x2apic cluster mode on platforms
 			supporting x2apic.
diff --git a/include/linux/workqueue.h b/include/linux/workqueue.h
index fc0136b604f2..623488fdc1f5 100644
--- a/include/linux/workqueue.h
+++ b/include/linux/workqueue.h
@@ -303,33 +303,6 @@ enum {
 	WQ_CPU_INTENSIVE	= 1 << 5, /* cpu instensive workqueue */
 	WQ_SYSFS		= 1 << 6, /* visible in sysfs, see wq_sysfs_register() */
 
-	/*
-	 * Per-cpu workqueues are generally preferred because they tend to
-	 * show better performance thanks to cache locality.  Per-cpu
-	 * workqueues exclude the scheduler from choosing the CPU to
-	 * execute the worker threads, which has an unfortunate side effect
-	 * of increasing power consumption.
-	 *
-	 * The scheduler considers a CPU idle if it doesn't have any task
-	 * to execute and tries to keep idle cores idle to conserve power;
-	 * however, for example, a per-cpu work item scheduled from an
-	 * interrupt handler on an idle CPU will force the scheduler to
-	 * excute the work item on that CPU breaking the idleness, which in
-	 * turn may lead to more scheduling choices which are sub-optimal
-	 * in terms of power consumption.
-	 *
-	 * Workqueues marked with WQ_POWER_EFFICIENT are per-cpu by default
-	 * but become unbound if workqueue.power_efficient kernel param is
-	 * specified.  Per-cpu workqueues which are identified to
-	 * contribute significantly to power-consumption are identified and
-	 * marked with this flag and enabling the power_efficient mode
-	 * leads to noticeable power saving at the cost of small
-	 * performance disadvantage.
-	 *
-	 * http://thread.gmane.org/gmane.linux.kernel/1480396
-	 */
-	WQ_POWER_EFFICIENT	= 1 << 7,
-
 	__WQ_DRAINING		= 1 << 16, /* internal: workqueue is draining */
 	__WQ_ORDERED		= 1 << 17, /* internal: workqueue is ordered */
 
diff --git a/kernel/power/Kconfig b/kernel/power/Kconfig
index 46455961a88f..5dfdc9ea180b 100644
--- a/kernel/power/Kconfig
+++ b/kernel/power/Kconfig
@@ -263,26 +263,6 @@ 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
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 8068d97ce141..4aa9f5bc6b2d 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -272,15 +272,6 @@ static cpumask_var_t *wq_numa_possible_cpumask;
 static bool wq_disable_numa;
 module_param_named(disable_numa, wq_disable_numa, bool, 0444);
 
-/* see the comment above the definition of WQ_POWER_EFFICIENT */
-#ifdef CONFIG_WQ_POWER_EFFICIENT_DEFAULT
-static bool wq_power_efficient = true;
-#else
-static bool wq_power_efficient;
-#endif
-
-module_param_named(power_efficient, wq_power_efficient, bool, 0444);
-
 static bool wq_numa_enabled;		/* unbound NUMA affinity enabled */
 
 /* buf for wq_update_unbound_numa_attrs(), protected by CPU hotplug exclusion */
@@ -4094,10 +4085,6 @@ struct workqueue_struct *__alloc_workqueue_key(const char *fmt,
 	struct workqueue_struct *wq;
 	struct pool_workqueue *pwq;
 
-	/* see the comment above the definition of WQ_POWER_EFFICIENT */
-	if ((flags & WQ_POWER_EFFICIENT) && wq_power_efficient)
-		flags |= WQ_UNBOUND;
-
 	/* allocate wq and format name */
 	if (flags & WQ_UNBOUND)
 		tbl_size = wq_numa_tbl_len * sizeof(wq->numa_pwq_tbl[0]);