| Message ID | 1645171838-2855-1-git-send-email-wanpengli@tencent.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | x86/kvm: Don't use pv tlb/ipi/sched_yield if on 1 vCPU | expand |
On 2/18/22 09:10, Wanpeng Li wrote: > From: Wanpeng Li <wanpengli@tencent.com> > > Inspired by commit 3553ae5690a (x86/kvm: Don't use pvqspinlock code if > only 1 vCPU), on a VM with only 1 vCPU, there is no need to enable > pv tlb/ipi/sched_yield and we can save the memory for __pv_cpu_mask. > > Signed-off-by: Wanpeng Li <wanpengli@tencent.com> > --- > arch/x86/kernel/kvm.c | 9 ++++++--- > 1 file changed, 6 insertions(+), 3 deletions(-) > > diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c > index a438217cbfac..f734e3b0cfec 100644 > --- a/arch/x86/kernel/kvm.c > +++ b/arch/x86/kernel/kvm.c > @@ -462,19 +462,22 @@ static bool pv_tlb_flush_supported(void) > { > return (kvm_para_has_feature(KVM_FEATURE_PV_TLB_FLUSH) && > !kvm_para_has_hint(KVM_HINTS_REALTIME) && > - kvm_para_has_feature(KVM_FEATURE_STEAL_TIME)); > + kvm_para_has_feature(KVM_FEATURE_STEAL_TIME) && > + (num_possible_cpus() != 1)); > } > > static bool pv_ipi_supported(void) > { > - return kvm_para_has_feature(KVM_FEATURE_PV_SEND_IPI); > + return (kvm_para_has_feature(KVM_FEATURE_PV_SEND_IPI) && > + (num_possible_cpus() != 1)); > } > > static bool pv_sched_yield_supported(void) > { > return (kvm_para_has_feature(KVM_FEATURE_PV_SCHED_YIELD) && > !kvm_para_has_hint(KVM_HINTS_REALTIME) && > - kvm_para_has_feature(KVM_FEATURE_STEAL_TIME)); > + kvm_para_has_feature(KVM_FEATURE_STEAL_TIME) && > + (num_possible_cpus() != 1)); > } > > #define KVM_IPI_CLUSTER_SIZE (2 * BITS_PER_LONG) Queued, thanks. Paolo
diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c index a438217cbfac..f734e3b0cfec 100644 --- a/arch/x86/kernel/kvm.c +++ b/arch/x86/kernel/kvm.c @@ -462,19 +462,22 @@ static bool pv_tlb_flush_supported(void) { return (kvm_para_has_feature(KVM_FEATURE_PV_TLB_FLUSH) && !kvm_para_has_hint(KVM_HINTS_REALTIME) && - kvm_para_has_feature(KVM_FEATURE_STEAL_TIME)); + kvm_para_has_feature(KVM_FEATURE_STEAL_TIME) && + (num_possible_cpus() != 1)); } static bool pv_ipi_supported(void) { - return kvm_para_has_feature(KVM_FEATURE_PV_SEND_IPI); + return (kvm_para_has_feature(KVM_FEATURE_PV_SEND_IPI) && + (num_possible_cpus() != 1)); } static bool pv_sched_yield_supported(void) { return (kvm_para_has_feature(KVM_FEATURE_PV_SCHED_YIELD) && !kvm_para_has_hint(KVM_HINTS_REALTIME) && - kvm_para_has_feature(KVM_FEATURE_STEAL_TIME)); + kvm_para_has_feature(KVM_FEATURE_STEAL_TIME) && + (num_possible_cpus() != 1)); } #define KVM_IPI_CLUSTER_SIZE (2 * BITS_PER_LONG)