From: Peter Zijlstra <a.p.zijlstra@chello.nl>
To: Hillf Danton <dhillf@gmail.com>
Cc: Rik van Riel <riel@redhat.com>,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
Avi Kiviti <avi@redhat.com>,
Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>,
Mike Galbraith <efault@gmx.de>,
Chris Wright <chrisw@sous-sol.org>
Subject: Re: [RFC -v3 PATCH 2/3] sched: add yield_to function
Date: Tue, 04 Jan 2011 18:22:17 +0100 [thread overview]
Message-ID: <1294161737.2016.177.camel@laptop> (raw)
In-Reply-To: <AANLkTimJMF+4VQ39zTRorqFXYKy9sJ1xwUWTxyUG4M2R@mail.gmail.com>
On Wed, 2011-01-05 at 01:12 +0800, Hillf Danton wrote:
> On Wed, Jan 5, 2011 at 1:08 AM, Peter Zijlstra <a.p.zijlstra@chello.nl> wrote:
> > On Wed, 2011-01-05 at 00:51 +0800, Hillf Danton wrote:
> >> Where is the yield_to callback in the patch for RT schedule class?
> >> If @p is RT, what could you do?
> >
> > RT guests are a pipe dream, you first need to get the hypervisor (kvm in
> > this case) to be RT, which it isn't. Then you either need to very
> > statically set-up the host and the guest scheduling constraints (not
> > possible with RR/FIFO) or have a complete paravirt RT scheduler which
> > communicates its requirements to the host.
> >
> Even guest is not RT, you could not prevent it from being preempted by
> RT task which has nothing to do guests.
Sure, but yield_to() being a NOP for RT tasks is perfectly fine. Pretty
much all yield*() usage is a bug anyway.
next prev parent reply other threads:[~2011-01-04 17:22 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-01-03 21:26 [RFC -v3 PATCH 0/3] directed yield for Pause Loop Exiting Rik van Riel
2011-01-03 21:27 ` [RFC -v3 PATCH 1/3] kvm: keep track of which task is running a KVM vcpu Rik van Riel
2011-01-03 21:29 ` [RFC -v3 PATCH 2/3] sched: add yield_to function Rik van Riel
2011-01-04 1:51 ` Mike Galbraith
2011-01-04 6:14 ` KOSAKI Motohiro
2011-01-04 12:03 ` Avi Kivity
2011-01-05 2:39 ` KOSAKI Motohiro
2011-01-05 8:35 ` Avi Kivity
2011-01-05 8:40 ` KOSAKI Motohiro
2011-01-05 9:08 ` Avi Kivity
2011-01-05 9:30 ` KOSAKI Motohiro
2011-01-05 9:34 ` Avi Kivity
2011-01-05 10:24 ` Peter Zijlstra
2011-01-05 10:04 ` Peter Zijlstra
2011-01-04 17:16 ` Peter Zijlstra
2011-01-05 3:17 ` KOSAKI Motohiro
2011-01-04 14:28 ` Hillf Danton
2011-01-04 16:41 ` Hillf Danton
2011-01-04 16:44 ` Rik van Riel
2011-01-04 16:51 ` Hillf Danton
2011-01-04 16:54 ` Rik van Riel
2011-01-04 17:02 ` Hillf Danton
2011-01-04 17:08 ` Peter Zijlstra
2011-01-04 17:12 ` Hillf Danton
2011-01-04 17:22 ` Peter Zijlstra [this message]
2011-01-04 17:53 ` Rik van Riel
2011-01-04 18:05 ` Peter Zijlstra
2011-01-04 18:04 ` Peter Zijlstra
2011-01-04 18:53 ` Mike Galbraith
2011-01-05 16:57 ` Mike Galbraith
2011-01-05 17:04 ` Peter Zijlstra
2011-01-05 17:23 ` Mike Galbraith
2011-01-07 5:29 ` Mike Galbraith
2011-01-13 3:02 ` Rik van Riel
2011-01-13 3:26 ` Mike Galbraith
2011-01-13 5:08 ` Rik van Riel
2011-01-06 14:33 ` Hillf Danton
2011-01-05 17:10 ` Avi Kivity
2011-01-05 17:15 ` Peter Zijlstra
2011-01-05 17:19 ` Avi Kivity
2011-01-05 17:28 ` Peter Zijlstra
2011-01-05 17:35 ` Avi Kivity
2011-01-05 17:39 ` Peter Zijlstra
2011-01-06 3:49 ` Tejun Heo
2011-01-03 21:30 ` [RFC -v3 PATCH 3/3] Subject: kvm: use yield_to instead of sleep in kvm_vcpu_on_spin Rik van Riel
2011-01-04 6:42 ` [RFC -v3 PATCH 0/3] directed yield for Pause Loop Exiting Mike Galbraith
2011-01-04 9:09 ` Avi Kivity
2011-01-04 10:32 ` Mike Galbraith
2011-01-04 10:35 ` Avi Kivity
2011-01-04 9:14 ` Avi Kivity
2011-01-04 10:26 ` Mike Galbraith
2011-01-04 17:20 ` Peter Zijlstra
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