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cpuidle-haltpoll: Enable kvm guest polling when dedicated physical CPUs are available

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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.

Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This commit is contained in:
Wanpeng Li 2019-08-29 16:49:57 +08:00 committed by Rafael J. Wysocki
parent 472f263660
commit 1328edca4a
2 changed files with 3 additions and 1 deletions
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1
arch/x86/kernel/kvm.c
View File

@ -711,6 +711,7 @@ unsigned int kvm_arch_para_hints(void)
{
return cpuid_edx(kvm_cpuid_base() | KVM_CPUID_FEATURES);
}
EXPORT_SYMBOL_GPL(kvm_arch_para_hints);
static uint32_t __init kvm_detect(void)
{

3
drivers/cpuidle/cpuidle-haltpoll.c
View File

@ -97,7 +97,8 @@ 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 -ENODEV;
ret = cpuidle_register_driver(drv);