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Groups > linux.kernel > #1628106
| From | Paolo Bonzini <pbonzini@redhat.com> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [PATCH v6] kvm: better MWAIT emulation for guests |
| Date | 2017-04-21 12:10 +0200 |
| Message-ID | <tyDFM-4xX-17@gated-at.bofh.it> (permalink) |
| References | (3 earlier) <tvrB8-5Bn-3@gated-at.bofh.it> <tvrUu-5IE-33@gated-at.bofh.it> <tvtjA-6IX-29@gated-at.bofh.it> <tyDFL-4xX-5@gated-at.bofh.it> <tyDFL-4xX-3@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
On 21/04/2017 12:05, Alexander Graf wrote:
>
>
> On 21.04.17 12:02, Paolo Bonzini wrote:
>>
>>
>> On 12/04/2017 18:29, Michael S. Tsirkin wrote:
>>> I don't really agree we do not need the PV flag. mwait on kvm is
>>> different from mwait on bare metal in that you are heavily penalized by
>>> scheduler for polling unless you configure the host just so.
>>> HLT lets you give up the host CPU if you know you won't need
>>> it for a long time.
>>>
>>> So while many people can get by with monitor cpuid (those that isolate
>>> host CPUs) and it's a valuable option to have, I think a PV flag is also
>>> a valuable option and can be set for more configurations.
>>>
>>> Guest has an idle driver calling mwait on short waits and halt on longer
>>> ones. I'm in fact testing an idle driver using such a PV flag and will
>>> post when ready (after vacation ~3 weeks from now probably).
>>
>> For now I think I'm removing the PV flag, making this just an
>> optimization of commit 87c00572ba05aa8c ("kvm: x86: emulate
>> monitor and mwait instructions as nop").
>>
>> We can add it for 4.13 together with the idle driver.
>
> I think that's a perfectly reasonable approach, yes. We can always add
> the PV flag with the driver.
>
> Thanks a lot!
Queuing the patch for 4.12.
Paolo
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[PATCH v6] kvm: better MWAIT emulation for guests Alexander Graf <agraf@suse.de> - 2017-04-11 13:50 +0200
Re: [PATCH v6] kvm: better MWAIT emulation for guests Alexander Graf <agraf@suse.de> - 2017-04-11 14:50 +0200
Re: [PATCH v6] kvm: better MWAIT emulation for guests "Gabriel L. Somlo" <gsomlo@gmail.com> - 2017-04-11 14:50 +0200
Re: [PATCH v6] kvm: better MWAIT emulation for guests "Gabriel L. Somlo" <gsomlo@gmail.com> - 2017-04-11 14:50 +0200
Re: [PATCH v6] kvm: better MWAIT emulation for guests Jim Mattson <jmattson@google.com> - 2017-04-11 19:20 +0200
Re: [PATCH v6] kvm: better MWAIT emulation for guests Alexander Graf <agraf@suse.de> - 2017-04-11 20:30 +0200
Re: [PATCH v6] kvm: better MWAIT emulation for guests Jim Mattson <jmattson@google.com> - 2017-04-12 16:40 +0200
Re: [PATCH v6] kvm: better MWAIT emulation for guests Alexander Graf <agraf@suse.de> - 2017-04-12 17:00 +0200
Re: [PATCH v6] kvm: better MWAIT emulation for guests Jim Mattson <jmattson@google.com> - 2017-04-12 17:30 +0200
Re: [PATCH v6] kvm: better MWAIT emulation for guests "Michael S. Tsirkin" <mst@redhat.com> - 2017-04-12 18:30 +0200
Re: [PATCH v6] kvm: better MWAIT emulation for guests Alexander Graf <agraf@suse.de> - 2017-04-21 12:10 +0200
Re: [PATCH v6] kvm: better MWAIT emulation for guests Paolo Bonzini <pbonzini@redhat.com> - 2017-04-21 12:10 +0200
Re: [PATCH v6] kvm: better MWAIT emulation for guests Paolo Bonzini <pbonzini@redhat.com> - 2017-04-21 12:10 +0200
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