Re: [PATCH 2/2] firmware_class: Move request_firmware_nowait() toworkqueues
From: Tejun Heo
Date: Tue Mar 27 2012 - 18:48:40 EST
On Wed, Mar 28, 2012 at 12:21:27AM +0200, Rafael J. Wysocki wrote:
> On Wednesday, March 28, 2012, Tejun Heo wrote:
> > On Tue, Mar 27, 2012 at 02:28:30PM -0700, Stephen Boyd wrote:
> > > Oddly enough a work_struct was already part of the firmware_work
> > > structure but nobody was using it. Instead of creating a new
> > > kthread for each request_firmware_nowait() call just schedule the
> > > work on the long system workqueue. This should avoid some overhead
> > > in forking new threads when they're not strictly necessary.
> > >
> > > Signed-off-by: Stephen Boyd <sboyd@xxxxxxxxxxxxxx>
> > > ---
> > >
> > > Is it better to use alloc_workqueue() and not put these on the system
> > > long workqueue?
> > No, just use schedule_work() unless there are specific requirements
> > which can't be fulfilled that way (e.g. it's on memory allocation
> > path, may consume large amount of cpu cycles, ...)
> It may wait quite long.
That shouldn't matter. system_long_wq's name is a bit misleading at
this point. The only reason it's used currently is to avoid cyclic
dependency involving flush_workqueue(), which calls for clearer
solution anyway. So, yeap, using system_wq should be fine here.
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