On Wed, 18 May, at 03:01:27AM, Yuyang Du wrote:
> On Tue, May 17, 2016 at 01:24:15PM +0100, Matt Fleming wrote:
> > So, if the code looks like the following, either now or in the future,
> >
> > static void __schedule(bool preempt)
> > {
> > ...
> > /* Clear RQCF_ACT_SKIP */
> > rq->clock_update_flags = 0;
> > ...
> > delta = rq_clock();
> > }
>
> Sigh, you even said "Clear RQCF_ACT_SKIP", but you not only clear it,
> you clear everything.
That was sloppy on my part but intentional because that's what the
code looks like in tip/sched/core today.
It was purely meant to demonstrate that setting RQCF_UPDATE just
because RQCF_ACT_SKIP is set does not make sense. You can replace the
clearing line with the correct bit masking operation.
But I get it, the pseudo-code was confusing. I'll send out a v2.
> And if you clear the RQCF_UPDATE also (maybe you shouldn't, but
> actually it does not matter), of course you will get a warning...
Right, I wouldn't actually clear RQCF_UPDATE in v2 of this patch.
> In addition, it looks like multiple skips are possible, so:
I'm not sure what you mean, could you elaborate?
> update_rq_clock() {
> rq->clock_update_flags |= RQCF_UPDATE;
>
> ...
> }
>
> instead of clearing the skip flag there.
Huh? RQCF_*_SKIP are not cleared in update_rq_clock().
