From: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
To: Rik van Riel <riel@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
Avi Kiviti <avi@redhat.com>,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
Ingo Molnar <mingo@elte.hu>,
Anthony Liguori <aliguori@linux.vnet.ibm.com>
Subject: Re: [RFC PATCH 2/3] sched: add yield_to function
Date: Fri, 3 Dec 2010 23:15:34 +0530 [thread overview]
Message-ID: <20101203174534.GD11725@linux.vnet.ibm.com> (raw)
In-Reply-To: <4CF929E9.6000603@redhat.com>
On Fri, Dec 03, 2010 at 12:33:29PM -0500, Rik van Riel wrote:
> >Anyway, the intention of yield() proposed was not to get lock released
> >immediately (which will happen eventually), but rather to avoid inefficiency
> >associated with (long) spinning and at the same time make sure we are not
> >leaking our bandwidth to other guests because of a naive yield ..
>
> A KVM guest can run on the host alongside short-lived
> processes, though. How can we ensure that a VCPU that
> donates time gets it back again later, when the task
> time was donated to may no longer exist?
I think that does not matter. What matters for fairness in this case is how much
cpu time yielding thread gets over some (larger) time window. By ensuring that
relinquished time is fedback, we should maintian fairness for that particular
vcpu thread ..This also avoids nasty interactions associated with donation ..
- vatsa
next prev parent reply other threads:[~2010-12-03 17:45 UTC|newest]
Thread overview: 60+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-12-02 19:41 [RFC PATCH 0/3] directed yield for Pause Loop Exiting Rik van Riel
2010-12-02 19:43 ` [RFC PATCH 1/3] kvm: keep track of which task is running a KVM vcpu Rik van Riel
2010-12-03 1:18 ` Chris Wright
2010-12-03 14:50 ` Rik van Riel
2010-12-03 15:55 ` Chris Wright
2010-12-05 12:40 ` Avi Kivity
2010-12-03 12:17 ` Srivatsa Vaddagiri
2010-12-03 14:16 ` Rik van Riel
2010-12-05 12:59 ` Avi Kivity
2010-12-02 19:44 ` [RFC PATCH 2/3] sched: add yield_to function Rik van Riel
2010-12-03 0:50 ` Chris Wright
2010-12-03 18:27 ` Rik van Riel
2010-12-03 19:30 ` Chris Wright
2010-12-03 21:30 ` Peter Zijlstra
2010-12-03 5:54 ` Mike Galbraith
2010-12-03 13:46 ` Srivatsa Vaddagiri
2010-12-03 14:45 ` Mike Galbraith
2010-12-03 14:48 ` Rik van Riel
2010-12-03 15:09 ` Mike Galbraith
2010-12-03 15:35 ` Rik van Riel
2010-12-03 16:20 ` Srivatsa Vaddagiri
2010-12-03 17:09 ` Rik van Riel
2010-12-03 17:29 ` Srivatsa Vaddagiri
2010-12-03 17:33 ` Rik van Riel
2010-12-03 17:45 ` Srivatsa Vaddagiri [this message]
2010-12-03 20:05 ` Mike Galbraith
2010-12-03 21:26 ` Peter Zijlstra
2010-12-03 13:23 ` Peter Zijlstra
2010-12-03 13:30 ` Srivatsa Vaddagiri
2010-12-03 14:03 ` Peter Zijlstra
2010-12-03 14:06 ` Srivatsa Vaddagiri
2010-12-03 14:10 ` Srivatsa Vaddagiri
2010-12-03 21:23 ` Peter Zijlstra
2010-12-04 13:02 ` Rik van Riel
2010-12-10 4:34 ` Rik van Riel
2010-12-10 8:39 ` Srivatsa Vaddagiri
2010-12-10 14:55 ` Rik van Riel
2010-12-08 17:55 ` Rik van Riel
2010-12-08 20:00 ` Peter Zijlstra
2010-12-08 20:04 ` Peter Zijlstra
2010-12-08 22:59 ` Rik van Riel
2010-12-02 19:45 ` [RFC PATCH 3/3] kvm: use yield_to instead of sleep in kvm_vcpu_on_spin Rik van Riel
2010-12-03 2:24 ` Chris Wright
2010-12-05 12:58 ` Avi Kivity
2010-12-05 12:56 ` Avi Kivity
2010-12-08 22:38 ` Rik van Riel
2010-12-09 10:28 ` Avi Kivity
2010-12-09 17:07 ` Rik van Riel
2010-12-11 7:27 ` Avi Kivity
2010-12-02 22:41 ` [RFC PATCH 0/3] directed yield for Pause Loop Exiting Chris Wright
2010-12-05 13:02 ` Avi Kivity
2010-12-10 5:03 ` Balbir Singh
2010-12-10 14:54 ` Rik van Riel
2010-12-11 7:31 ` Avi Kivity
2010-12-11 13:57 ` Balbir Singh
2010-12-13 11:57 ` Avi Kivity
2010-12-13 12:39 ` Balbir Singh
2010-12-13 12:42 ` Avi Kivity
2010-12-13 17:02 ` Rik van Riel
2010-12-14 9:25 ` Balbir Singh
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