Messages in this thread | | | Subject | Re: [PATCH] cpuidle-haltpoll: Enable kvm guest polling when dedicated physical CPUs are available | From | Paolo Bonzini <> | Date | Thu, 1 Aug 2019 18:54:49 +0200 |
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On 01/08/19 18:51, Rafael J. Wysocki wrote: > On 8/1/2019 9:06 AM, Wanpeng Li wrote: >> From: Wanpeng Li <wanpengli@tencent.com> >> >> 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@intel.com> >> Cc: Paolo Bonzini <pbonzini@redhat.com> >> Cc: Radim Krčmář <rkrcmar@redhat.com> >> Cc: Marcelo Tosatti <mtosatti@redhat.com> >> Signed-off-by: Wanpeng Li <wanpengli@tencent.com> > > Paolo, Marcelo, any comments?
Yes, it's a good idea.
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
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; > >
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