From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from na01-bn1-obe.outbound.protection.outlook.com (mail-bn1blp0182.outbound.protection.outlook.com [207.46.163.182]) (using TLSv1 with cipher AES128-SHA (128/128 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 54DEC1A0006 for ; Wed, 18 Jun 2014 05:10:07 +1000 (EST) From: Mihai Caraman To: Subject: [PATCH v3] KVM: PPC: e500mc: Enhance tlb invalidation condition on vcpu schedule Date: Tue, 17 Jun 2014 22:09:36 +0300 Message-ID: <1403032176-28362-1-git-send-email-mihai.caraman@freescale.com> MIME-Version: 1.0 Content-Type: text/plain Cc: Scott Wood , Mihai Caraman , linuxppc-dev@lists.ozlabs.org, kvm@vger.kernel.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , 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_on_cpu 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 Cc: Scott Wood --- v3: - use existing logic while keeping last_vcpu_per_cpu per lpid v2: - improve patch name and description - add performance results arch/powerpc/kvm/e500mc.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/arch/powerpc/kvm/e500mc.c b/arch/powerpc/kvm/e500mc.c index 17e4562..95e33e3 100644 --- a/arch/powerpc/kvm/e500mc.c +++ b/arch/powerpc/kvm/e500mc.c @@ -110,7 +110,7 @@ void kvmppc_mmu_msr_notify(struct kvm_vcpu *vcpu, u32 old_msr) { } -static DEFINE_PER_CPU(struct kvm_vcpu *, last_vcpu_on_cpu); +static DEFINE_PER_CPU(struct kvm_vcpu * [KVMPPC_NR_LPIDS], last_vcpu_on_cpu); static void kvmppc_core_vcpu_load_e500mc(struct kvm_vcpu *vcpu, int cpu) { @@ -141,9 +141,9 @@ static void kvmppc_core_vcpu_load_e500mc(struct kvm_vcpu *vcpu, int cpu) mtspr(SPRN_GESR, vcpu->arch.shared->esr); if (vcpu->arch.oldpir != mfspr(SPRN_PIR) || - __get_cpu_var(last_vcpu_on_cpu) != vcpu) { + __get_cpu_var(last_vcpu_on_cpu)[vcpu->kvm->arch.lpid] != vcpu) { kvmppc_e500_tlbil_all(vcpu_e500); - __get_cpu_var(last_vcpu_on_cpu) = vcpu; + __get_cpu_var(last_vcpu_on_cpu)[vcpu->kvm->arch.lpid] = vcpu; } kvmppc_load_guest_fp(vcpu); -- 1.7.11.7