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@xxxxxxxxxxxxx>
> ---
> 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;
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