From patchwork Fri May 8 17:03:55 2009 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mark Langsdorf X-Patchwork-Id: 22625 Received: from vger.kernel.org (vger.kernel.org [209.132.176.167]) by demeter.kernel.org (8.14.2/8.14.2) with ESMTP id n48H3lK8001259 for ; Fri, 8 May 2009 17:03:47 GMT Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759433AbZEHRC6 (ORCPT ); Fri, 8 May 2009 13:02:58 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753596AbZEHRC6 (ORCPT ); Fri, 8 May 2009 13:02:58 -0400 Received: from outbound-dub.frontbridge.com ([213.199.154.16]:40640 "EHLO IE1EHSOBE005.bigfish.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1762859AbZEHRCz convert rfc822-to-8bit (ORCPT ); Fri, 8 May 2009 13:02:55 -0400 Received: from mail189-dub-R.bigfish.com (10.5.252.3) by IE1EHSOBE005.bigfish.com (10.5.252.25) with Microsoft SMTP Server id 8.1.340.0; Fri, 8 May 2009 17:02:54 +0000 Received: from mail189-dub (localhost.localdomain [127.0.0.1]) by mail189-dub-R.bigfish.com (Postfix) with ESMTP id 66594C30109; Fri, 8 May 2009 17:02:53 +0000 (UTC) X-BigFish: VPS1(zz936fJzz1202hzzz32i6bh43j63h) X-Spam-TCS-SCL: 2:0 Received: by mail189-dub (MessageSwitch) id 1241802170371545_7924; Fri, 8 May 2009 17:02:50 +0000 (UCT) Received: from ausb3extmailp01.amd.com (unknown [163.181.251.8]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by mail189-dub.bigfish.com (Postfix) with ESMTP id 1BB2FF68065; Fri, 8 May 2009 17:02:48 +0000 (UTC) Received: from ausb3twp02.amd.com ([163.181.250.38]) by ausb3extmailp01.amd.com (Switch-3.2.7/Switch-3.2.7) with ESMTP id n48H0rFY013272; Fri, 8 May 2009 12:02:05 -0500 X-WSS-ID: 0KJC4L9-02-CQC-01 Received: from sausexbh2.amd.com (SAUSEXBH2.amd.com [163.181.22.102]) by ausb3twp02.amd.com (Tumbleweed MailGate 3.5.1) with ESMTP id 2551216A042C; Fri, 8 May 2009 12:00:44 -0500 (CDT) Received: from sausexmb4.amd.com ([163.181.3.15]) by sausexbh2.amd.com with Microsoft SMTPSVC(6.0.3790.3959); Fri, 8 May 2009 12:00:53 -0500 Received: from wshpnow.amd.com ([10.236.48.99]) by sausexmb4.amd.com with Microsoft SMTPSVC(6.0.3790.3959); Fri, 8 May 2009 12:00:53 -0500 From: Mark Langsdorf To: Joerg Roedel Subject: [PATCH][KVM][retry 2] Add support for Pause Filtering to AMD SVM Date: Fri, 8 May 2009 12:03:55 -0500 User-Agent: KMail/1.9.10 CC: avi@redhat.com, kvm@vger.kernel.org, linux-kernel@vger.kernel.org References: <200905050909.58583.mark.langsdorf@amd.com> <20090507135522.GJ4059@amd.com> <200905071000.14038.mark.langsdorf@amd.com> In-Reply-To: <200905071000.14038.mark.langsdorf@amd.com> MIME-Version: 1.0 Content-Disposition: inline Message-ID: <200905081203.55484.mark.langsdorf@amd.com> X-OriginalArrivalTime: 08 May 2009 17:00:53.0698 (UTC) FILETIME=[8C2A1220:01C9CFFE] Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org From 01813db8627e74018c8cec90df7e345839351f23 Mon Sep 17 00:00:00 2001 From: Mark Langsdorf Date: Thu, 7 May 2009 09:44:10 -0500 Subject: [PATCH] Add support for Pause Filtering to AMD SVM This feature creates a new field in the VMCB called Pause Filter Count. If Pause Filter Count is greater than 0 and intercepting PAUSEs is enabled, the processor will increment an internal counter when a PAUSE instruction occurs instead of intercepting. When the internal counter reaches the Pause Filter Count value, a PAUSE intercept will occur. This feature can be used to detect contended spinlocks, especially when the lock holding VCPU is not scheduled. Rescheduling another VCPU prevents the VCPU seeking the lock from wasting its quantum by spinning idly. Experimental results show that most spinlocks are held for less than 1000 PAUSE cycles or more than a few thousand. Default the Pause Filter Counter to 3000 to detect the contended spinlocks. Processor support for this feature is indicated by a CPUID bit. On a 24 core system running 4 guests each with 16 VCPUs, this patch improved overall performance of each guest's 32 job kernbench by approximately 1%. Further performance improvement may be possible with a more sophisticated yield algorithm. -Mark Langsdorf Operating System Research Center AMD Signed-off-by: Mark Langsdorf --- arch/x86/include/asm/svm.h | 3 ++- arch/x86/kvm/svm.c | 17 +++++++++++++++++ virt/kvm/kvm_main.c | 2 ++ 3 files changed, 21 insertions(+), 1 deletions(-) diff --git a/arch/x86/include/asm/svm.h b/arch/x86/include/asm/svm.h index 85574b7..1fecb7e 100644 --- a/arch/x86/include/asm/svm.h +++ b/arch/x86/include/asm/svm.h @@ -57,7 +57,8 @@ struct __attribute__ ((__packed__)) vmcb_control_area { u16 intercept_dr_write; u32 intercept_exceptions; u64 intercept; - u8 reserved_1[44]; + u8 reserved_1[42]; + u16 pause_filter_count; u64 iopm_base_pa; u64 msrpm_base_pa; u64 tsc_offset; diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c index ef43a18..4279141 100644 --- a/arch/x86/kvm/svm.c +++ b/arch/x86/kvm/svm.c @@ -45,6 +45,7 @@ MODULE_LICENSE("GPL"); #define SVM_FEATURE_NPT (1 << 0) #define SVM_FEATURE_LBRV (1 << 1) #define SVM_FEATURE_SVML (1 << 2) +#define SVM_FEATURE_PAUSE_FILTER (1 << 10) #define DEBUGCTL_RESERVED_BITS (~(0x3fULL)) @@ -575,6 +576,12 @@ static void init_vmcb(struct vcpu_svm *svm) svm->nested_vmcb = 0; svm->vcpu.arch.hflags = HF_GIF_MASK; + + if (svm_has(SVM_FEATURE_PAUSE_FILTER)) { + control->pause_filter_count = 5000; + control->intercept |= (1ULL << INTERCEPT_PAUSE); + } + } static int svm_vcpu_reset(struct kvm_vcpu *vcpu) @@ -2087,6 +2094,15 @@ static int interrupt_window_interception(struct vcpu_svm *svm, return 1; } +static int pause_interception(struct vcpu_svm *svm, struct kvm_run *kvm_run) +{ + /* Simple yield */ + vcpu_put(&svm->vcpu); + schedule(); + vcpu_load(&svm->vcpu); + return 1; +} + static int (*svm_exit_handlers[])(struct vcpu_svm *svm, struct kvm_run *kvm_run) = { [SVM_EXIT_READ_CR0] = emulate_on_interception, @@ -2123,6 +2139,7 @@ static int (*svm_exit_handlers[])(struct vcpu_svm *svm, [SVM_EXIT_CPUID] = cpuid_interception, [SVM_EXIT_IRET] = iret_interception, [SVM_EXIT_INVD] = emulate_on_interception, + [SVM_EXIT_PAUSE] = pause_interception, [SVM_EXIT_HLT] = halt_interception, [SVM_EXIT_INVLPG] = invlpg_interception, [SVM_EXIT_INVLPGA] = invalid_op_interception, diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 2b73e19..e2b730d 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -710,6 +710,7 @@ void vcpu_load(struct kvm_vcpu *vcpu) kvm_arch_vcpu_load(vcpu, cpu); put_cpu(); } +EXPORT_SYMBOL_GPL(vcpu_load); void vcpu_put(struct kvm_vcpu *vcpu) { @@ -719,6 +720,7 @@ void vcpu_put(struct kvm_vcpu *vcpu) preempt_enable(); mutex_unlock(&vcpu->mutex); } +EXPORT_SYMBOL_GPL(vcpu_put); static void ack_flush(void *_completed) {