Messages in this thread | | | Subject | Re: [PATCH v4 3/3] KVM: X86: Don't use PV TLB flush with dedicated vCPUs and steal time disabled | From | Paolo Bonzini <> | Date | Tue, 13 Feb 2018 17:12:43 +0100 |
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On 13/02/2018 02:05, Wanpeng Li wrote: > From: Wanpeng Li <wanpengli@tencent.com> > > vCPUs are very unlikely to get preempted when they are the only task > running on a CPU. PV TLB flush is slower that the native flush in that > case. In addition, avoid traversing all the cpus for pv tlb flush when > steal time is disabled since pv tlb flush depends on the field in steal > time for shared data. > > Cc: Paolo Bonzini <pbonzini@redhat.com> > Cc: Radim Krčmář <rkrcmar@redhat.com> > Cc: Eduardo Habkost <ehabkost@redhat.com> > Signed-off-by: Wanpeng Li <wanpengli@tencent.com> > --- > arch/x86/kernel/kvm.c | 8 ++++++-- > 1 file changed, 6 insertions(+), 2 deletions(-) > > diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c > index c5566d9..285822f 100644 > --- a/arch/x86/kernel/kvm.c > +++ b/arch/x86/kernel/kvm.c > @@ -545,7 +545,9 @@ static void __init kvm_guest_init(void) > pv_time_ops.steal_clock = kvm_steal_clock; > } > > - if (kvm_para_has_feature(KVM_FEATURE_PV_TLB_FLUSH)) > + if (kvm_para_has_feature(KVM_FEATURE_PV_TLB_FLUSH) && > + !kvm_para_has_feature(KVM_HINTS_DEDICATED) && > + !kvm_para_has_feature(KVM_FEATURE_STEAL_TIME)) > pv_mmu_ops.flush_tlb_others = kvm_flush_tlb_others; > > if (kvm_para_has_feature(KVM_FEATURE_PV_EOI)) > @@ -638,7 +640,9 @@ static __init int kvm_setup_pv_tlb_flush(void) > { > int cpu; > > - if (kvm_para_has_feature(KVM_FEATURE_PV_TLB_FLUSH)) { > + if (kvm_para_has_feature(KVM_FEATURE_PV_TLB_FLUSH) && > + !kvm_para_has_feature(KVM_HINTS_DEDICATED) &&
This should have checked the hints word.
In general, I'm going to change in the whole series kvm_hint_has_feature with kvm_para_has_hint, and kvm_arch_hint_features with kvm_arch_para_hints. But apart from this small naming issue, the series looks good, and I'm applying it to kvm/queue.
Paolo
> + !kvm_para_has_feature(KVM_FEATURE_STEAL_TIME)) { > for_each_possible_cpu(cpu) { > zalloc_cpumask_var_node(per_cpu_ptr(&__pv_tlb_mask, cpu), > GFP_KERNEL, cpu_to_node(cpu)); >
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