Messages in this thread Patch in this message | | | Date | Mon, 18 Oct 2010 10:44:04 +0100 | From | Mel Gorman <> | Subject | Re: [PATCH v2.6.36-rc7] memory_hotplug: drop spurious calls to flush_scheduled_work() |
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On Fri, Oct 15, 2010 at 05:25:15PM +0200, Tejun Heo wrote: > lru_add_drain_all() uses schedule_on_each_cpu() which is synchronous. > There is no reason to call flush_scheduled_work() after > lru_add_drain_all(). Drop the spurious calls. >
This looks correct.
Acked-by: Mel Gorman <mel@csn.ul.ie>
I suspect this call to flush_scheduled_work() existed because it is easy to interpret the documentation of schedule_on_each_cpu to mean it is an asynchronous call. Maybe something like the following?
==== CUT HERE ==== workqueue: Clarify that schedule_on_each_cpu is synchronous
The documentation for schedule_on_each_cpu() states that it calls a function on each online CPU from keventd. This can easily be interpreted as an asyncronous call because the description does not mention that flush_work is called. Clarify that it is synchronous.
Signed-off-by: Mel Gorman <mel@csn.ul.ie> --- kernel/workqueue.c | 8 +++++--- 1 files changed, 5 insertions(+), 3 deletions(-)
diff --git a/kernel/workqueue.c b/kernel/workqueue.c index f77afd9..07cba1e 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -2592,13 +2592,15 @@ int schedule_delayed_work_on(int cpu, EXPORT_SYMBOL(schedule_delayed_work_on); /** - * schedule_on_each_cpu - call a function on each online CPU from keventd + * schedule_on_each_cpu - Call a function on each online CPU via keventd and wait for completion * @func: the function to call * + * schedule_on_each_cpu executes a given callback function on each CPU via keventd + * and blocks until each callback has completed. schedule_on_each_cpu() is very + * slow. + * * Returns zero on success. * Returns -ve errno on failure. - * - * schedule_on_each_cpu() is very slow. */ int schedule_on_each_cpu(work_func_t func) {
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