From: Rik van Riel <riel@redhat.com>
To: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
Avi Kiviti <avi@redhat.com>,
Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>,
Chris Wright <chrisw@sous-sol.org>
Subject: Re: [RFC -v3 PATCH 2/3] sched: add yield_to function
Date: Thu, 13 Jan 2011 00:08:58 -0500 [thread overview]
Message-ID: <4D2E88EA.3050604@redhat.com> (raw)
In-Reply-To: <1294889169.8089.10.camel@marge.simson.net>
On 01/12/2011 10:26 PM, Mike Galbraith wrote:
> On Wed, 2011-01-12 at 22:02 -0500, Rik van Riel wrote:
>
>> Cgroups only makes the matter worse - libvirt places
>> each KVM guest into its own cgroup, so a VCPU will
>> generally always be alone on its own per-cgroup, per-cpu
>> runqueue! That can lead to pulling a VCPU onto our local
>> CPU because we think we are alone, when in reality we
>> share the CPU with others...
>
> How can that happen? If the task you're trying to accelerate isn't in
> your task group, the whole attempt should be a noop.
Nono, all the VCPUs from the same guest are in the same
cgroup. However, with 4 VCPUs and 4 physical CPUs,
chances are that they're all alone on their own per-cpu,
per-cgroup cfs_rq.
However, each CPU might have other runnable processes in
other cfs_rq sched entities.
--
All rights reversed
next prev parent reply other threads:[~2011-01-13 5:09 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
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 [this message]
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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