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Date: Fri, 21 Jan 2011 09:48:29 -0500
From: Rik van Riel <riel@redhat.com>
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CC: Jeremy Fitzhardinge <jeremy@goop.org>,
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Subject: Re: [PATCH 2/3] kvm hypervisor : Add hypercalls to support pv-ticketlock
References: <cover.1289940821.git.jeremy.fitzhardinge@citrix.com> <20110119164432.GA30669@linux.vnet.ibm.com> <20110119171239.GB726@linux.vnet.ibm.com> <1295457672.28776.144.camel@laptop> <4D373340.60608@goop.org> <20110120115958.GB11177@linux.vnet.ibm.com> <4D38774B.6070704@goop.org> <20110121140208.GA13609@linux.vnet.ibm.com>
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On 01/21/2011 09:02 AM, Srivatsa Vaddagiri wrote:
> On Thu, Jan 20, 2011 at 09:56:27AM -0800, Jeremy Fitzhardinge wrote:
>>>   The key here is not to
>>> sleep when waiting for locks (as implemented by current patch-series, which can
>>> put other VMs at an advantage by giving them more time than they are entitled
>>> to)
>>
>> Why?  If a VCPU can't make progress because its waiting for some
>> resource, then why not schedule something else instead?
>
> In the process, "something else" can get more share of cpu resource than its
> entitled to and that's where I was bit concerned. I guess one could
> employ hard-limits to cap "something else's" bandwidth where it is of real
> concern (like clouds).

I'd like to think I fixed those things in my yield_task_fair +
yield_to + kvm_vcpu_on_spin patch series from yesterday.

https://lkml.org/lkml/2011/1/20/403

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