* Peter Zijlstra <pet...@infradead.org> wrote:
> On Thu, Jun 27, 2013 at 12:43:09PM +0200, Peter Zijlstra wrote:
> > On Wed, Jun 26, 2013 at 10:46:33AM -0600, David Ahern wrote:
> > > On 6/26/13 1:05 AM, Peter Zijlstra wrote:
> > > >>What is the expectation that the feature provides? not a whole lot of
> > > >>documentation on it. I walked down the path wondering if it solved an
> > > >>odd
> > > >>problem we are seeing with the CFS in 2.6.27 kernel.
> > > >
> > > >Its supposed to use hrtimers for slice expiry instead of the regular
> > > >tick.
> > >
> > > So theoretically CPU bound tasks would get preempted sooner? That was my
> > > guess/hope anyways.
> >
> > Doth the below worketh?
> >
>
> Related to all this; the reason its not enabled by default is that
> mucking about with hrtimers all the while is god awful expensive.
>
> I've had ideas about making this a special purpose 'hard-coded' timer in
> the hrtimer guts that's only ever re-programmed when the new value is
> sooner.
>
> By making it a 'special' timer we can avoid the whole rb-tree song and
> dance; and by taking 'spurious' short interrupts we can avoid prodding
> the hardware too often.
Sounds neat ...
> Then again; Thomas will likely throw frozen seafood my way for even
> proposing stuff like this and I'm not even sure that's going to be
> enough to make the cost acceptable.
(Could be worse: rotten seafood?)
Thanks,
Ingo
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