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xen-devel
[Xen-devel] Re: [PATCH RFC V2 3/5] kvm hypervisor : Add two hypercalls t
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To: |
Raghavendra K T <raghukt@xxxxxxxxxxxxxxxxxx> |
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Subject: |
[Xen-devel] Re: [PATCH RFC V2 3/5] kvm hypervisor : Add two hypercalls to support pv-ticketlock |
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From: |
Avi Kivity <avi@xxxxxxxxxx> |
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Date: |
Thu, 27 Oct 2011 12:17:15 +0200 |
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Cc: |
Raghavendra K T <raghavendra.kt@xxxxxxxxxxxxxxxxxx>, KVM <kvm@xxxxxxxxxxxxxxx>, Peter Zijlstra <peterz@xxxxxxxxxxxxx>, Srivatsa Vaddagiri <vatsa@xxxxxxxxxxxxxxxxxx>, "H. Peter Anvin" <hpa@xxxxxxxxx>, Jeremy Fitzhardinge <jeremy.fitzhardinge@xxxxxxxxxx>, Dave Jiang <dave.jiang@xxxxxxxxx>, Gleb Natapov <gleb@xxxxxxxxxx>, x86@xxxxxxxxxx, Ingo Molnar <mingo@xxxxxxxxxx>, Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>, Marcelo Tosatti <mtosatti@xxxxxxxxxx>, Xen <xen-devel@xxxxxxxxxxxxxxxxxxx>, Sedat Dilek <sedat.dilek@xxxxxxxxx>, Thomas Gleixner <tglx@xxxxxxxxxxxxx>, Virtualization <virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx>, Yinghai Lu <yinghai@xxxxxxxxxx>, Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>, Greg Kroah-Hartman <gregkh@xxxxxxx>, LKML <linux-kernel@xxxxxxxxxxxxxxx>, Suzuki Poulose <suzuki@xxxxxxxxxxxxxxxxxx>, Ryan Harper <ryanh@xxxxxxxxxx> |
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Thu, 27 Oct 2011 05:38:53 -0700 |
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References: |
<20111023190307.16364.35381.sendpatchset@xxxxxxxxxxxxxxxxxxxx> <20111023190558.16364.2136.sendpatchset@xxxxxxxxxxxxxxxxxxxx> <4EA53A7D.300@xxxxxxxxxx> <20111024122734.GA10634@xxxxxxxxxxxxxxxxxx> <4EA56385.9040302@xxxxxxxxxx> <20111024135032.GB10634@xxxxxxxxxxxxxxxxxx> <4EA6FEC2.1060209@xxxxxxxxxxxxxxxxxx> <4EA7E21B.8020805@xxxxxxxxxx> <4EA85A9D.5060203@xxxxxxxxxxxxxxxxxx> |
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On 10/26/2011 09:08 PM, Raghavendra K T wrote:
> On 10/26/2011 04:04 PM, Avi Kivity wrote:
>> On 10/25/2011 08:24 PM, Raghavendra K T wrote:
> CCing Ryan also
>>>
>>> So then do also you foresee the need for directed yield at some point,
>>> to address LHP? provided we have good improvements to prove.
>>
>> Doesn't this patchset completely eliminate lock holder preemption?
>>
> Basically I was curious whether we can do more better with your
> directed yield discussions in https://lkml.org/lkml/2010/8/2/106 .
>
> I felt we can get little more improvement with doing directed yield to
> lock-holder in case of LHP than sleeping. But I may be wrong.
>
> So wanted to get the feedback, on whether I am thinking in right
> direction.
i guess donating some time to the lock holder could help, but not by
much. The problem with non-pv spinlocks is that you can't just sleep,
since no one will wake you up, so you have to actively boost the lock
holder.
--
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.
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