Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]
Groups > linux.kernel > #1431156
| From | Peter Zijlstra <peterz@infradead.org> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [PATCH] locking/osq: Drop the overload of osq lock |
| Date | 2016-06-25 18:10 +0200 |
| Message-ID | <rNYjD-7B7-9@gated-at.bofh.it> (permalink) |
| References | <rNW89-66B-11@gated-at.bofh.it> <rNWKR-6yX-1@gated-at.bofh.it> <rNXxf-751-3@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
On Sat, Jun 25, 2016 at 11:21:30PM +0800, Boqun Feng wrote:
> >
> > int vpc = vcpu_preempt_count();
> >
> > ...
> >
> > for (;;) {
> >
> > /* the big spin loop */
> >
> > if (need_resched() || vpc != vcpu_preempt_count())
>
> So on PPC, we have lppaca::yield_count to detect when an vcpu is
Which sounds like just the value we want.. And I suspect that on x86 KVM
and Xen have similar numbers stashed away someplace.
> preempted, if the yield_count is even, the vcpu is running, otherwise it
> is preempted(__spin_yield() is a user of this).
>
> Therefore it makes more sense we
>
> if (need_resched() || vcpu_is_preempted(old))
>
> here, and implement vcpu_is_preempted() on PPC as
>
> bool vcpu_is_preempted(int cpu)
> {
> return !!(be32_to_cpu(lppaca_of(cpu).yield_count) & 1)
> }
>
> Thoughts?
That works here, but it would not work for the need_resched() in
mutex_spin_on_owner() and mutex_optimistic_spin() which need equal
treatment.
Because those too we want to limit.
The count thing, while a little more cumbersome, is more widely
applicable than just the one OSQ case where we happen to have a cpu
number.
Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread
[PATCH] locking/osq: Drop the overload of osq lock Pan Xinhui <xinhui.pan@linux.vnet.ibm.com> - 2016-06-25 15:50 +0200
Re: [PATCH] locking/osq: Drop the overload of osq lock Peter Zijlstra <peterz@infradead.org> - 2016-06-25 16:30 +0200
Re: [PATCH] locking/osq: Drop the overload of osq lock Boqun Feng <boqun.feng@gmail.com> - 2016-06-25 17:20 +0200
Re: [PATCH] locking/osq: Drop the overload of osq lock Peter Zijlstra <peterz@infradead.org> - 2016-06-25 18:10 +0200
Re: [PATCH] locking/osq: Drop the overload of osq lock Peter Zijlstra <peterz@infradead.org> - 2016-06-25 18:20 +0200
Re: [PATCH] locking/osq: Drop the overload of osq lock panxinhui <xinhui@linux.vnet.ibm.com> - 2016-06-25 19:30 +0200
Re: [PATCH] locking/osq: Drop the overload of osq lock Peter Zijlstra <peterz@infradead.org> - 2016-06-25 21:20 +0200
Re: [PATCH] locking/osq: Drop the overload of osq lock panxinhui <xinhui@linux.vnet.ibm.com> - 2016-06-26 07:00 +0200
Re: [PATCH] locking/osq: Drop the overload of osq lock Peter Zijlstra <peterz@infradead.org> - 2016-06-27 10:00 +0200
Re: [PATCH] locking/osq: Drop the overload of osq lock xinhui <xinhui.pan@linux.vnet.ibm.com> - 2016-06-27 12:30 +0200
Re: [PATCH] locking/osq: Drop the overload of osq lock Boqun Feng <boqun.feng@gmail.com> - 2016-06-25 18:30 +0200
Re: [PATCH] locking/osq: Drop the overload of osq lock Peter Zijlstra <peterz@infradead.org> - 2016-06-25 20:30 +0200
Re: [PATCH] locking/osq: Drop the overload of osq lock Peter Zijlstra <peterz@infradead.org> - 2016-06-25 18:20 +0200
Re: [PATCH] locking/osq: Drop the overload of osq lock Boqun Feng <boqun.feng@gmail.com> - 2016-06-25 18:50 +0200
Re: [PATCH] locking/osq: Drop the overload of osq lock panxinhui <xinhui@linux.vnet.ibm.com> - 2016-06-25 19:30 +0200
Re: [PATCH] locking/osq: Drop the overload of osq lock Peter Zijlstra <peterz@infradead.org> - 2016-06-25 21:30 +0200
Re: [PATCH] locking/osq: Drop the overload of osq lock Peter Zijlstra <peterz@infradead.org> - 2016-06-25 21:40 +0200
Re: [PATCH] locking/osq: Drop the overload of osq lock Boqun Feng <boqun.feng@gmail.com> - 2016-06-26 04:30 +0200
Re: [PATCH] locking/osq: Drop the overload of osq lock panxinhui <xinhui@linux.vnet.ibm.com> - 2016-06-26 07:30 +0200
Re: [PATCH] locking/osq: Drop the overload of osq lock Boqun Feng <boqun.feng@gmail.com> - 2016-06-26 08:10 +0200
Re: [PATCH] locking/osq: Drop the overload of osq lock panxinhui <xinhui@linux.vnet.ibm.com> - 2016-06-26 09:00 +0200
Re: [PATCH] locking/osq: Drop the overload of osq lock Boqun Feng <boqun.feng@gmail.com> - 2016-06-26 16:10 +0200
Re: [PATCH] locking/osq: Drop the overload of osq lock panxinhui <xinhui@linux.vnet.ibm.com> - 2016-06-26 18:00 +0200
Re: [PATCH] locking/osq: Drop the overload of osq lock Boqun Feng <boqun.feng@gmail.com> - 2016-06-26 09:00 +0200
Re: [PATCH] locking/osq: Drop the overload of osq lock panxinhui <xinhui@linux.vnet.ibm.com> - 2016-06-26 09:10 +0200
Re: [PATCH] locking/osq: Drop the overload of osq lock Boqun Feng <boqun.feng@gmail.com> - 2016-06-26 16:30 +0200
Re: [PATCH] locking/osq: Drop the overload of osq lock panxinhui <xinhui@linux.vnet.ibm.com> - 2016-06-26 17:20 +0200
Re: [PATCH] locking/osq: Drop the overload of osq lock Boqun Feng <boqun.feng@gmail.com> - 2016-06-27 08:50 +0200
Re: [PATCH] locking/osq: Drop the overload of osq lock xinhui <xinhui.pan@linux.vnet.ibm.com> - 2016-06-27 09:40 +0200
Re: [PATCH] locking/osq: Drop the overload of osq lock Peter Zijlstra <peterz@infradead.org> - 2016-06-27 10:20 +0200
Re: [PATCH] locking/osq: Drop the overload of osq lock Boqun Feng <boqun.feng@gmail.com> - 2016-06-27 12:30 +0200
csiph-web