* A problem about optimize the kvm_vcpu_on_spin
@ 2016-11-14 1:44 Longpeng (Mike)
2016-11-14 8:56 ` Paolo Bonzini
0 siblings, 1 reply; 3+ messages in thread
From: Longpeng (Mike) @ 2016-11-14 1:44 UTC (permalink / raw)
To: Paolo Bonzini, Radim Krčmář; +Cc: Wubin (H), zhaoshenglong, kvm
Hi Paolo and Radim,
Intel sdm vol3 ch-25.1.3 (p-1074) said: The “PAUSE-loop exiting” VM-execution
control is ignored if CPL > 0.
Does this means that only guest's kernelspace spinlock could causes VMexit due
to "pause-loop exiting" ?
If so, I think the kvm_vcpu_on_spin should selects a (currently not running)vcpu
which cpl=0 to boost, because the cpl>0 vcpus are not the lock-holder. (suppose
the guest isn't RT-linux)
What about your opinion ?
--
Regards,
Longpeng(Mike)
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: A problem about optimize the kvm_vcpu_on_spin
2016-11-14 1:44 A problem about optimize the kvm_vcpu_on_spin Longpeng (Mike)
@ 2016-11-14 8:56 ` Paolo Bonzini
2016-11-14 9:30 ` Longpeng (Mike)
0 siblings, 1 reply; 3+ messages in thread
From: Paolo Bonzini @ 2016-11-14 8:56 UTC (permalink / raw)
To: Longpeng (Mike)
Cc: Radim Krčmář, Wubin (H), zhaoshenglong, kvm
> Intel sdm vol3 ch-25.1.3 (p-1074) said: The “PAUSE-loop exiting” VM-execution
> control is ignored if CPL > 0.
>
> Does this means that only guest's kernelspace spinlock could causes VMexit
> due to "pause-loop exiting" ?
>
> If so, I think the kvm_vcpu_on_spin should selects a (currently not
> running) vcpu which cpl=0 to boost, because the cpl>0 vcpus are not
> the lock-holder. (suppose the guest isn't RT-linux)
>
> What about your opinion ?
Yes, that's a good idea!
Paolo
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: A problem about optimize the kvm_vcpu_on_spin
2016-11-14 8:56 ` Paolo Bonzini
@ 2016-11-14 9:30 ` Longpeng (Mike)
0 siblings, 0 replies; 3+ messages in thread
From: Longpeng (Mike) @ 2016-11-14 9:30 UTC (permalink / raw)
To: Paolo Bonzini; +Cc: Radim Krčmář, Wubin (H), zhaoshenglong, kvm
On 2016/11/14 16:56, Paolo Bonzini wrote:
>
>> Intel sdm vol3 ch-25.1.3 (p-1074) said: The “PAUSE-loop exiting” VM-execution
>> control is ignored if CPL > 0.
>>
>> Does this means that only guest's kernelspace spinlock could causes VMexit
>> due to "pause-loop exiting" ?
>>
>> If so, I think the kvm_vcpu_on_spin should selects a (currently not
>> running) vcpu which cpl=0 to boost, because the cpl>0 vcpus are not
>> the lock-holder. (suppose the guest isn't RT-linux)
>>
>> What about your opinion ?
>
> Yes, that's a good idea!
>
> Paolo
Thanks, I will send a RFC this week.
>
> .
>
--
Regards,
Longpeng(Mike)
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2016-11-14 9:31 UTC | newest]
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2016-11-14 1:44 A problem about optimize the kvm_vcpu_on_spin Longpeng (Mike)
2016-11-14 8:56 ` Paolo Bonzini
2016-11-14 9:30 ` Longpeng (Mike)
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