Re: [PATCH -v5][RFC]: mutex: implement adaptive spinning

Peter W. Morreale
2009-01-07T22:51:28Z

On Wed, 2009-01-07 at 23:33 +0100, Ingo Molnar wrote:
> * Gregory Haskins <ghaskins@novell.com> wrote:
>
> > Can I ask a simple question in light of all this discussion?
> >
> > "Is get_task_struct() really that bad?"
>
> it dirties a cacheline and it also involves atomics.
>
> Also, it's a small design cleanliness issue to me: get_task_struct()
> impacts the lifetime of an object - and if a locking primitive has
> side-effects on object lifetimes that's never nice.
>

True, but it's for one iteration * NR_CPUS, max.

Best,
-PWM

> Ingo
>