On Thu, Apr 25, 2013 at 9:13 AM, Viresh Kumar viresh.kumar@linaro.org wrote:
On 25 April 2013 09:00, Amit Kucheria amit.kucheria@linaro.org wrote:
Yes. That was my intention - preventing a prompt on existing defconfigs and there by maintaining current behavior.
Hmm... Following is the version after fixing all problems you reported. @Tejun: I have attached it too as gmail's copy-paste may break it. Please consider applying this series if it looks fine to you.
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From: Viresh Kumar viresh.kumar@linaro.org Date: Mon, 8 Apr 2013 16:45:40 +0530 Subject: [PATCH V5 1/5] workqueues: Introduce new flag WQ_POWER_EFFICIENT for power oriented workqueues
Workqueues can be performance or power-oriented. Currently, most workqueues are bound to the CPU they were created on. This gives good performance (due to cache effects) at the cost of potentially waking up otherwise idle cores just to process some work. To save power, we can allow the work to be rescheduled on a core that is already awake.
Workqueues created with the WQ_UNBOUND flag will allow some power savings. However, we don't change the default behaviour of the system. To enable power-saving behaviour, a new config option CONFIG_WQ_POWER_EFFICIENT needs to be turned on. This option can also be overridden by the workqueue.power_efficient boot parameter.
Signed-off-by: Viresh Kumar viresh.kumar@linaro.org
For the series, you can add my:
Reviewed-by: Amit Kucheria amit.kucheria@linaro.org
Documentation/kernel-parameters.txt | 17 +++++++++++++++++ include/linux/workqueue.h | 3 +++ kernel/power/Kconfig | 19 +++++++++++++++++++ kernel/workqueue.c | 11 +++++++++++ 4 files changed, 50 insertions(+)
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index c4fa000..22edc83 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -3312,6 +3312,23 @@ 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_efficientWorkqueues can be performance or power-oriented.Currently, most workqueues are bound to the CPU theywere created on. This gives good performance (due tocache effects) at the cost of potentially waking upotherwise idle cores just to process some work. To savepower, we can allow the work to be rescheduled on a corethat is already awake.Workqueues created with the WQ_UNBOUND flag will allowsome power savings. However, we don't change thedefault behaviour of the system. To enable power-savingbehaviour, a new config option CONFIG_WQ_POWER_EFFICIENTneeds to be turned on. This option can also beoverridden by the workqueue.power_efficient bootparameter.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 623488f..83fa570 100644 --- a/include/linux/workqueue.h +++ b/include/linux/workqueue.h @@ -302,6 +302,9 @@ enum { WQ_HIGHPRI = 1 << 4, /* high priority */ WQ_CPU_INTENSIVE = 1 << 5, /* cpu instensive workqueue */ WQ_SYSFS = 1 << 6, /* visible in sysfs, see wq_sysfs_register() */
WQ_POWER_EFFICIENT = 1 << 7, /* WQ_UNBOUND, for power* saving, if wq_power_efficient is* enabled. Unused otherwise. */ __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 5dfdc9e..018f039 100644 --- a/kernel/power/Kconfig +++ b/kernel/power/Kconfig @@ -263,6 +263,25 @@ config PM_GENERIC_DOMAINS bool depends on PM
+config WQ_POWER_EFFICIENT
bool "Workqueue allocated as UNBOUND (by default) for power efficiency"depends on PMdefault nhelpWorkqueues can be performance or power-oriented. Currently, mostworkqueues are bound to the CPU they were created on. This gives goodperformance (due to cache effects) at the cost of potentially wakingup otherwise idle cores just to process some work. To save power, wecan allow the work to be rescheduled on a core that is already awake.Workqueues created with the WQ_UNBOUND flag will allow some powersavings. However, we don't change the default behaviour of thesystem. To enable power-saving behaviour, a new config optionCONFIG_WQ_POWER_EFFICIENT needs to be turned on. This option can alsobe overridden by the workqueue.power_efficient boot parameter.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 4aa9f5b..a327027 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -272,6 +272,14 @@ static cpumask_var_t *wq_numa_possible_cpumask; static bool wq_disable_numa; module_param_named(disable_numa, wq_disable_numa, bool, 0444);
+#ifdef CONFIG_WQ_POWER_EFFICIENT +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 */ @@ -4085,6 +4093,9 @@ struct workqueue_struct *__alloc_workqueue_key(const char *fmt, struct workqueue_struct *wq; struct pool_workqueue *pwq;
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]);