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Date: Fri, 04 May 2012 10:21:17 +0530 From: "Srivatsa S. Bhat" <srivatsa.bhat@...ux.vnet.ibm.com> To: Gilad Ben-Yossef <gilad@...yossef.com> CC: linux-kernel@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>, Tejun Heo <tj@...nel.org>, John Stultz <johnstul@...ibm.com>, Andrew Morton <akpm@...ux-foundation.org>, KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>, Mel Gorman <mel@....ul.ie>, Mike Frysinger <vapier@...too.org>, David Rientjes <rientjes@...gle.com>, Hugh Dickins <hughd@...gle.com>, Minchan Kim <minchan.kim@...il.com>, Konstantin Khlebnikov <khlebnikov@...nvz.org>, Christoph Lameter <cl@...ux.com>, Chris Metcalf <cmetcalf@...era.com>, Hakan Akkan <hakanakkan@...il.com>, Max Krasnyansky <maxk@...lcomm.com>, Frederic Weisbecker <fweisbec@...il.com>, linux-mm@...ck.org Subject: Re: [PATCH v1 3/6] workqueue: introduce schedule_on_each_cpu_cond On 05/03/2012 08:25 PM, Gilad Ben-Yossef wrote: > Introduce the schedule_on_each_cpu_cond() function that schedules > a work item on each online CPU for which the supplied condition > function returns true. > > This function should be used instead of schedule_on_each_cpu() > when only some of the CPUs have actual work to do and a predicate > function can tell if a certain CPU does or does not have work to do, > thus saving unneeded wakeups and schedules. > > Signed-off-by: Gilad Ben-Yossef <gilad@...yossef.com> > --- > diff --git a/kernel/workqueue.c b/kernel/workqueue.c > index 1c9782b..3322d30 100644 > --- a/kernel/workqueue.c > +++ b/kernel/workqueue.c > @@ -2828,6 +2828,43 @@ int schedule_on_each_cpu_mask(work_func_t func, const struct cpumask *mask) > } > > /** > + * schedule_on_each_cpu_cond - execute a function synchronously on each > + * online CPU for which the supplied condition function returns true > + * @func: the function to run on the selected CPUs > + * @cond_func: the function to call to select the CPUs > + * > + * schedule_on_each_cpu_cond() executes @func on each online CPU for > + * @cond_func returns true using the system workqueue and blocks until ^^^ (for) which Regards, Srivatsa S. Bhat > + * all CPUs have completed. > + * schedule_on_each_cpu_cond() is very slow. > + * > + * RETURNS: > + * 0 on success, -errno on failure. > + */ > +int schedule_on_each_cpu_cond(work_func_t func, bool (*cond_func)(int cpu)) > +{ > + int cpu, ret; > + cpumask_var_t mask; > + > + if (unlikely(!zalloc_cpumask_var(&mask, GFP_KERNEL))) > + return -ENOMEM; > + > + get_online_cpus(); > + > + for_each_online_cpu(cpu) > + if (cond_func(cpu)) > + cpumask_set_cpu(cpu, mask); > + > + ret = schedule_on_each_cpu_mask(func, mask); > + > + put_online_cpus(); > + > + free_cpumask_var(mask); > + > + return ret; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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