On Tue, Jul 29, 2014 at 07:37:33PM +0200, Peter Zijlstra wrote:
> On Tue, Jul 29, 2014 at 07:36:00PM +0200, Peter Zijlstra wrote:
> > On Tue, Jul 29, 2014 at 10:33:18AM -0700, Paul E. McKenney wrote:
> > > > No, but why can't we make the regular cond_resched() do this?
> > >
> > > Well, I got a lot of grief when I tried it a few weeks ago.
> > >
> > > But from what I can see, you are the maintainer or cond_resched(), so
> > > if you are good with making the normal cond_resched() do this, I am
> > > more than happy to make it so! ;-)
> >
> > Well, its the 'obvious' thing to do. But clearly I haven't tried so I'm
> > blissfully unaware of any problems. And the Changelog didn't inform me
> > either (you had a link in there, which I didn't read :-)
>
> Then again, last time we touched cond_resched() we had a scalability
> issue or somesuch, or am I misremembering things?
More overhead than scalability, but yes. That said, that was a much
heavier weight touch. A later version with only an access to per-CPU
variable turned out to have overhead below what could be measured.
But I am comfortable with the current approach that does not touch
cond_resched() as well.
Thanx, Paul
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