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KVM: PPC: e500mc: Enhance tlb invalidation condition on vcpu schedule
On vcpu schedule, the condition checked for tlb pollution is too loose. The tlb entries of a vcpu become polluted (vs stale) only when a different vcpu within the same logical partition runs in-between. Optimize the tlb invalidation condition keeping last_vcpu per logical partition id. With the new invalidation condition, a guest shows 4% performance improvement on P5020DS while running a memory stress application with the cpu oversubscribed, the other guest running a cpu intensive workload. Guest - old invalidation condition real 3.89 user 3.87 sys 0.01 Guest - enhanced invalidation condition real 3.75 user 3.73 sys 0.01 Host real 3.70 user 1.85 sys 0.00 The memory stress application accesses 4KB pages backed by 75% of available TLB0 entries: char foo[ENTRIES][4096] __attribute__ ((aligned (4096))); int main() { char bar; int i, j; for (i = 0; i < ITERATIONS; i++) for (j = 0; j < ENTRIES; j++) bar = foo[j][0]; return 0; } Signed-off-by: Mihai Caraman <mihai.caraman@freescale.com> Reviewed-by: Scott Wood <scottwood@freescale.com> Signed-off-by: Alexander Graf <agraf@suse.de>
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1 changed files with 3 additions and 3 deletions
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@ -110,7 +110,7 @@ void kvmppc_mmu_msr_notify(struct kvm_vcpu *vcpu, u32 old_msr)
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{
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}
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static DEFINE_PER_CPU(struct kvm_vcpu *, last_vcpu_on_cpu);
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static DEFINE_PER_CPU(struct kvm_vcpu *[KVMPPC_NR_LPIDS], last_vcpu_of_lpid);
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static void kvmppc_core_vcpu_load_e500mc(struct kvm_vcpu *vcpu, int cpu)
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{
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@ -141,9 +141,9 @@ static void kvmppc_core_vcpu_load_e500mc(struct kvm_vcpu *vcpu, int cpu)
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mtspr(SPRN_GESR, vcpu->arch.shared->esr);
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if (vcpu->arch.oldpir != mfspr(SPRN_PIR) ||
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__get_cpu_var(last_vcpu_on_cpu) != vcpu) {
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__get_cpu_var(last_vcpu_of_lpid)[vcpu->kvm->arch.lpid] != vcpu) {
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kvmppc_e500_tlbil_all(vcpu_e500);
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__get_cpu_var(last_vcpu_on_cpu) = vcpu;
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__get_cpu_var(last_vcpu_of_lpid)[vcpu->kvm->arch.lpid] = vcpu;
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}
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kvmppc_load_guest_fp(vcpu);
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