On 01/08/19 18:51, Rafael J. Wysocki wrote:
> On 8/1/2019 9:06 AM, Wanpeng Li wrote:
>> From: Wanpeng Li <wanpengli@xxxxxxxxxxx>
>>
>> The downside of guest side polling is that polling is performed even
>> with other runnable tasks in the host. However, even if poll in kvm
>> can aware whether or not other runnable tasks in the same pCPU, it
>> can still incur extra overhead in over-subscribe scenario. Now we can
>> just enable guest polling when dedicated pCPUs are available.
>>
>> Cc: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
>> Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx>
>> Cc: Radim Krčmář <rkrcmar@xxxxxxxxxx>
>> Cc: Marcelo Tosatti <mtosatti@xxxxxxxxxx>
>> Signed-off-by: Wanpeng Li <wanpengli@xxxxxxxxxxx>
>
> Paolo, Marcelo, any comments?
Yes, it's a good idea.
Acked-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Paolo
>
>> ---
>> drivers/cpuidle/cpuidle-haltpoll.c | 3 ++-
>> drivers/cpuidle/governors/haltpoll.c | 2 +-
>> 2 files changed, 3 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/cpuidle/cpuidle-haltpoll.c
>> b/drivers/cpuidle/cpuidle-haltpoll.c
>> index 9ac093d..7aee38a 100644
>> --- a/drivers/cpuidle/cpuidle-haltpoll.c
>> +++ b/drivers/cpuidle/cpuidle-haltpoll.c
>> @@ -53,7 +53,8 @@ static int __init haltpoll_init(void)
>> cpuidle_poll_state_init(drv);
>> - if (!kvm_para_available())
>> + if (!kvm_para_available() ||
>> + !kvm_para_has_hint(KVM_HINTS_REALTIME))
>> return 0;
>> ret = cpuidle_register(&haltpoll_driver, NULL);
>> diff --git a/drivers/cpuidle/governors/haltpoll.c
>> b/drivers/cpuidle/governors/haltpoll.c
>> index 797477b..685c7007 100644
>> --- a/drivers/cpuidle/governors/haltpoll.c
>> +++ b/drivers/cpuidle/governors/haltpoll.c
>> @@ -141,7 +141,7 @@ static struct cpuidle_governor haltpoll_governor = {
>> static int __init init_haltpoll(void)
>> {
>> - if (kvm_para_available())
>> + if (kvm_para_available() && kvm_para_has_hint(KVM_HINTS_REALTIME))
>> return cpuidle_register_governor(&haltpoll_governor);
>> return 0;
>
>
