From: Rik van Riel <riel@redhat.com>
To: Mike Galbraith <mgalbraith@suse.de>
Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
Avi Kiviti <avi@redhat.com>,
Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
Chris Wright <chrisw@sous-sol.org>
Subject: Re: [RFC -v2 PATCH 2/3] sched: add yield_to function
Date: Mon, 20 Dec 2010 10:40:15 -0500 [thread overview]
Message-ID: <4D0F78DF.9010908@redhat.com> (raw)
In-Reply-To: <1292570143.7772.84.camel@marge.simson.net>
On 12/17/2010 02:15 AM, Mike Galbraith wrote:
> BTW, with this vruntime donation thingy, what prevents a task from
> forking off accomplices who do nothing but wait for a wakeup and
> yield_to(exploit)?
>
> Even swapping vruntimes in the same cfs_rq is dangerous as hell, because
> one party is going backward.
I just realized the answer to this question.
We only give cpu time to tasks that are runnable, but not
currently running. That ensures one task cannot block others
from running by having time yielded to it constantly.
next prev parent reply other threads:[~2010-12-20 15:40 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-12-14 3:44 [RFC -v2 PATCH 0/3] directed yield for Pause Loop Exiting Rik van Riel
2010-12-14 3:45 ` [RFC -v2 PATCH 1/3] kvm: keep track of which task is running a KVM vcpu Rik van Riel
2010-12-14 3:46 ` [RFC -v2 PATCH 2/3] sched: add yield_to function Rik van Riel
2010-12-14 6:08 ` Mike Galbraith
2010-12-14 10:24 ` Srivatsa Vaddagiri
2010-12-14 11:03 ` Mike Galbraith
2010-12-14 11:26 ` Srivatsa Vaddagiri
2010-12-14 12:47 ` Mike Galbraith
2010-12-16 19:49 ` Rik van Riel
2010-12-17 6:56 ` Mike Galbraith
2010-12-17 7:15 ` Mike Galbraith
2010-12-18 17:08 ` Avi Kivity
2010-12-18 19:13 ` Mike Galbraith
2010-12-19 6:08 ` Avi Kivity
2010-12-20 15:40 ` Rik van Riel [this message]
2010-12-20 16:04 ` Mike Galbraith
2010-12-28 5:54 ` Mike Galbraith
2010-12-28 6:08 ` Gene Heskett
2010-12-28 6:16 ` Mike Galbraith
2010-12-28 16:18 ` Gene Heskett
2010-12-28 22:34 ` Rik van Riel
2010-12-17 15:09 ` Avi Kivity
2010-12-17 19:51 ` Mike Galbraith
2010-12-18 17:02 ` Avi Kivity
2010-12-18 19:06 ` Mike Galbraith
2010-12-19 6:21 ` Avi Kivity
2010-12-19 10:05 ` Mike Galbraith
2010-12-19 9:19 ` Avi Kivity
2010-12-19 11:18 ` Mike Galbraith
2010-12-20 8:39 ` Mike Galbraith
2010-12-20 8:45 ` Avi Kivity
2010-12-20 8:55 ` Mike Galbraith
2010-12-20 9:03 ` Avi Kivity
2010-12-20 9:30 ` Mike Galbraith
2010-12-20 9:46 ` Avi Kivity
2010-12-20 10:33 ` Mike Galbraith
2010-12-20 10:39 ` Avi Kivity
2010-12-20 10:46 ` Mike Galbraith
2010-12-20 10:49 ` Avi Kivity
2010-12-20 10:50 ` Mike Galbraith
2010-12-20 11:06 ` Avi Kivity
2010-12-14 12:22 ` Peter Zijlstra
2010-12-18 14:50 ` Rik van Riel
2010-12-14 3:48 ` [RFC -v2 PATCH 3/3] kvm: use yield_to instead of sleep in kvm_vcpu_on_spin Rik van Riel
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