Re: [RFC] sched: make callers check lock contention for cond_resched_lock()

Ingo Molnar
2012-05-18T07:26:10Z

* Takuya Yoshikawa <takuya.yoshikawa@gmail.com> wrote:

> Replaced Ingo's address with kernel.org one,
>
> On Thu, 03 May 2012 17:47:30 +0200
> Peter Zijlstra <peterz@infradead.org> wrote:
>
> > On Thu, 2012-05-03 at 22:00 +0900, Takuya Yoshikawa wrote:
> > > But as I could not see why spin_needbreak() was differently
> > > implemented
> > > depending on CONFIG_PREEMPT, I wanted to understand the meaning.
> >
> > Its been that way since before voluntary preemption was introduced, so
> > its possible Ingo simply missed that spot and nobody noticed until now.
> >
> > Ingo, do you have any recollections from back when?
>
> ping

I'm not sure we had a usable spin_is_contended() back then, nor
was the !PREEMPT case in my mind really.

( The patch looks ugly though, in 99% of the lines it just does
something that cond_resched_lock() itself could do. )

Thanks,

Ingo