From: Peter Zijlstra <peterz@infradead.org>
To: Boqun Feng <boqun.feng@gmail.com>
Cc: Pan Xinhui <xinhui.pan@linux.vnet.ibm.com>,
linux-kernel@vger.kernel.org, mingo@redhat.com,
dave@stgolabs.net, will.deacon@arm.com, Waiman.Long@hpe.com,
benh@kernel.crashing.org
Subject: Re: [PATCH] locking/osq: Drop the overload of osq lock
Date: Sat, 25 Jun 2016 20:28:39 +0200 [thread overview]
Message-ID: <20160625182839.GN30154@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <20160625162813.GC2384@insomnia>
On Sun, Jun 26, 2016 at 12:28:13AM +0800, Boqun Feng wrote:
> On Sat, Jun 25, 2016 at 06:09:22PM +0200, Peter Zijlstra wrote:
> > 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.
> >
>
> But if we don't have a cpu number, which vcpu's preemption are we
> trying to detect?
_this_ vcpu's preemption. If the yield count of this cpu changes, we
know this vcpu has been scheduled and we should stop spinning.
This is similar to the need_resched() case, which check is _this_ cpu
should reschedule.
next prev parent reply other threads:[~2016-06-25 18:28 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-06-25 17:42 Pan Xinhui
2016-06-25 14:24 ` Peter Zijlstra
2016-06-25 15:21 ` Boqun Feng
2016-06-25 16:09 ` Peter Zijlstra
2016-06-25 16:13 ` Peter Zijlstra
2016-06-25 17:27 ` panxinhui
2016-06-25 19:12 ` Peter Zijlstra
2016-06-26 4:59 ` panxinhui
2016-06-27 7:55 ` Peter Zijlstra
2016-06-27 10:19 ` xinhui
2016-06-25 16:28 ` Boqun Feng
2016-06-25 18:28 ` Peter Zijlstra [this message]
2016-06-25 16:15 ` Peter Zijlstra
2016-06-25 16:45 ` Boqun Feng
2016-06-25 17:27 ` panxinhui
2016-06-25 19:20 ` Peter Zijlstra
2016-06-25 19:29 ` Peter Zijlstra
2016-06-26 2:26 ` Boqun Feng
2016-06-26 5:21 ` panxinhui
2016-06-26 6:10 ` Boqun Feng
2016-06-26 6:58 ` panxinhui
2016-06-26 14:11 ` Boqun Feng
2016-06-26 15:54 ` panxinhui
2016-06-26 6:59 ` Boqun Feng
2016-06-26 7:08 ` panxinhui
2016-06-26 14:29 ` Boqun Feng
2016-06-26 15:11 ` panxinhui
2016-06-27 6:45 ` Boqun Feng
2016-06-27 7:36 ` xinhui
2016-06-27 8:09 ` Peter Zijlstra
2016-06-27 10:31 ` Boqun Feng
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