From mboxrd@z Thu Jan  1 00:00:00 1970
From: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Subject: Re: [RFC -v5 PATCH 2/4] sched: Add yield_to(task, preempt)
 functionality.
Date: Mon, 17 Jan 2011 21:23:16 +0530
Message-ID: <20110117155315.GA20416@linux.vnet.ibm.com>
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 <20110114030357.03c3060a@annuminas.surriel.com>
 <20110114174741.GB28632@linux.vnet.ibm.com>
 <4D309620.60507@redhat.com>
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Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
	Avi Kiviti <avi@redhat.com>,
	Peter Zijlstra <a.p.zijlstra@chello.nl>,
	Mike Galbraith <efault@gmx.de>,
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To: Rik van Riel <riel@redhat.com>
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On Fri, Jan 14, 2011 at 01:29:52PM -0500, Rik van Riel wrote:
> >I am not sure whether we are meeting that objective via this patch, as
> >lock-spinning vcpu would simply yield after setting next buddy to preferred
> >vcpu on target pcpu, thereby leaking some amount of bandwidth on the pcpu
> >where it is spinning.
> 
> Have you read the patch?

Sorry had mis-read the patch!

On reviewing it further, I am wondering if we can optimize yield_to() further
for case when target and current are on same pcpu, by swapping vruntimes of two
tasks (to let target run in current's place - as we do in task_fork_fair()).

- vatsa