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Re: [Qemu-devel] [QEMU patch 2/2] kvm: allow configuration of tsc deadli
From: |
Paolo Bonzini |
Subject: |
Re: [Qemu-devel] [QEMU patch 2/2] kvm: allow configuration of tsc deadline timer advancement |
Date: |
Wed, 10 Dec 2014 18:55:56 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.2.0 |
On 10/12/2014 18:35, Marcelo Tosatti wrote:
> On Wed, Dec 10, 2014 at 06:29:43PM +0100, Paolo Bonzini wrote:
>>
>>
>> On 10/12/2014 18:27, Marcelo Tosatti wrote:
>>> On Wed, Dec 10, 2014 at 06:09:19PM +0100, Paolo Bonzini wrote:
>>>>
>>>>
>>>> On 10/12/2014 18:04, Marcelo Tosatti wrote:
>>>>>> Please add an object property to the x86 CPU object. It can then be
>>>>>> configured with "-global" on the command line.
>>>>>
>>>>> Don't want to allow individual values for different CPUs.
>>>>> It is a per-VM property.
>>>>
>>>> Why? It can cause busy waiting, it would make sense to make it stricter
>>>> for realtime CPUs and leave 0 for non-realtime CPUs.
>>>
>>> HW timer behaviour should be consistent across CPUs, IMO.
>>
>> It's not going to be anyway. Cache line bounces, frequency scaling,
>> presence of higher-priority RT tasks, etc. can cause different response
>> for one CPU over the others.
>
> OK i'll change it to per-CPU.
Well, my preferred choice would be automatic adjustment with a module
parameter. If we need manual tuning, per-CPU would be my choice, but
automatic is nicer anyway. :)
Paolo
- [Qemu-devel] [QEMU patch 0/2] QEMU lapic tsc deadline advancement, Marcelo Tosatti, 2014/12/10
- [Qemu-devel] [QEMU patch 2/2] kvm: allow configuration of tsc deadline timer advancement, Marcelo Tosatti, 2014/12/10
- Re: [Qemu-devel] [QEMU patch 2/2] kvm: allow configuration of tsc deadline timer advancement, Paolo Bonzini, 2014/12/10
- Re: [Qemu-devel] [QEMU patch 2/2] kvm: allow configuration of tsc deadline timer advancement, Marcelo Tosatti, 2014/12/10
- Re: [Qemu-devel] [QEMU patch 2/2] kvm: allow configuration of tsc deadline timer advancement, Paolo Bonzini, 2014/12/10
- Re: [Qemu-devel] [QEMU patch 2/2] kvm: allow configuration of tsc deadline timer advancement, Marcelo Tosatti, 2014/12/10
- Re: [Qemu-devel] [QEMU patch 2/2] kvm: allow configuration of tsc deadline timer advancement, Paolo Bonzini, 2014/12/10
- Re: [Qemu-devel] [QEMU patch 2/2] kvm: allow configuration of tsc deadline timer advancement, Marcelo Tosatti, 2014/12/10
- Re: [Qemu-devel] [QEMU patch 2/2] kvm: allow configuration of tsc deadline timer advancement,
Paolo Bonzini <=
- Re: [Qemu-devel] [QEMU patch 2/2] kvm: allow configuration of tsc deadline timer advancement, Radim Krčmář, 2014/12/10
- Re: [Qemu-devel] [QEMU patch 2/2] kvm: allow configuration of tsc deadline timer advancement, Paolo Bonzini, 2014/12/10
Re: [Qemu-devel] [QEMU patch 2/2] kvm: allow configuration of tsc deadline timer advancement, Eric Blake, 2014/12/10
[Qemu-devel] [QEMU patch 1/2] kvm: sync kernel headers, Marcelo Tosatti, 2014/12/10