Re: [PATCH 6/7] sched: Clean up preempt_enable_no_resched() abuse

Peter Zijlstra
2013-11-22T11:31:00Z

On Fri, Nov 22, 2013 at 08:56:00AM +0200, Eliezer Tamir wrote:
> On 21/11/2013 15:39, Peter Zijlstra wrote:
> > On Thu, Nov 21, 2013 at 03:26:17PM +0200, Eliezer Tamir wrote:
>
> >> We don't override any limit the user has put on the system call.
> >
> > You are in fact, note how the normal select @endtime argument is only
> > set up _after_ you're done polling. So if the syscall had a timeout of 5
> > seconds, you just blew it by 55.
> >
>
> That's a bug, we will fix it.

The entire thing is a bug, and if I could take away sched_clock() from
you I would, but sadly its all inlines so I can't :-(

Please use local_clock(), yes its slightly more expensive, but I doubt
you can actually measure the effects on sane hardware.