lkml.org 
[lkml]   [2010]   [Jun]   [17]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: Overview of concurrency managed workqueue
On Thu, 17 Jun 2010 07:29:20 +0200
Florian Mickler <florian@mickler.org> wrote:

> On Wed, 16 Jun 2010 21:20:36 +0200
> Tejun Heo <tj@kernel.org> wrote:
>
> > On 06/16/2010 08:46 PM, Tejun Heo wrote:
> > > * I'm very sorry I'm breaking your hacky workaround but seriously
> > > that's another problem to solve. Let's talk about the problem
> > > itself instead of your hacky workaround. (I think for most cases
> > > not using workqueue in RT path would be the right thing to do.)
> >
> > For example, for the actual case of amba-pl022.c you mentioned, where
> > interrupt handler sometimes offloads to workqueue, convert
> > amba-pl022.c to use threaded interrupt handler. That's why it's
> > there.
> >
> > If you actually _solve_ the problem like this, other users wouldn't
> > experience the problem at all once the update reaches them and you
> > won't have to worry about your workaround breaking with the next
> > kernel update or unexpected suspend/resume and we won't be having this
> > discussion about adjusting workqueue priorities from userland.
> >
> > There are many wrong things about working around RT latency problems
> > by setting workqueue priorities from userland. Please think about why
> > the driver would have a separate workqueue for itself in the first
> > place. It was to work around the limitation of workqueue facility and
> > you're arguing that, because that work around allows yet another very
> > fragile workaround, the property which made the original work around
> > necessary in the first place needs to stay. That sounds really
> > perverse to me.
> >
>
> For what its worth, IMO the right thing to do would probably be to
> propagate the priority through the subsystem into the driver.

I was thinking about input devices here... anyway, my point is, that
the user of the workqueue-interface should pass the priority-context to
the workqueue subsystem...

If a userspace needs a driver to have a specific priority... can it
inform the system about it (thinking sysfs here..)? that would prevent
userspace having "to kick" the kernel if smth get's stuck....

Cheers,
Flo


\
 
 \ /
  Last update: 2010-06-17 08:25    [W:0.275 / U:0.116 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site