Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933143AbcKVMfx (ORCPT ); Tue, 22 Nov 2016 07:35:53 -0500 Received: from terminus.zytor.com ([198.137.202.10]:42206 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755640AbcKVMf2 (ORCPT ); Tue, 22 Nov 2016 07:35:28 -0500 Date: Tue, 22 Nov 2016 04:34:42 -0800 From: tip-bot for Pan Xinhui Message-ID: Cc: hpa@zytor.com, tglx@linutronix.de, torvalds@linux-foundation.org, linux-kernel@vger.kernel.org, mingo@kernel.org, xinhui.pan@linux.vnet.ibm.com, pbonzini@redhat.com, peterz@infradead.org Reply-To: tglx@linutronix.de, hpa@zytor.com, linux-kernel@vger.kernel.org, torvalds@linux-foundation.org, pbonzini@redhat.com, xinhui.pan@linux.vnet.ibm.com, mingo@kernel.org, peterz@infradead.org In-Reply-To: <1478077718-37424-10-git-send-email-xinhui.pan@linux.vnet.ibm.com> References: <1478077718-37424-10-git-send-email-xinhui.pan@linux.vnet.ibm.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:locking/core] x86/kvm: Support the vCPU preemption check Git-Commit-ID: 1885aa7041c9e801e5d5b093b9dad38937ca37f6 X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3513 Lines: 93 Commit-ID: 1885aa7041c9e801e5d5b093b9dad38937ca37f6 Gitweb: http://git.kernel.org/tip/1885aa7041c9e801e5d5b093b9dad38937ca37f6 Author: Pan Xinhui AuthorDate: Wed, 2 Nov 2016 05:08:36 -0400 Committer: Ingo Molnar CommitDate: Tue, 22 Nov 2016 12:48:08 +0100 x86/kvm: Support the vCPU preemption check Support the vcpu_is_preempted() functionality under KVM. This will enhance lock performance on overcommitted hosts (more runnable vCPUs than physical CPUs in the system) as doing busy waits for preempted vCPUs will hurt system performance far worse than early yielding. struct kvm_steal_time::preempted indicates that if one vCPU is running or not after commit "x86, kvm/x86.c: support vCPU preempted check". unix benchmark result: host: kernel 4.8.1, i5-4570, 4 cpus guest: kernel 4.8.1, 8 vcpus test-case after-patch before-patch Execl Throughput | 18307.9 lps | 11701.6 lps File Copy 1024 bufsize 2000 maxblocks | 1352407.3 KBps | 790418.9 KBps File Copy 256 bufsize 500 maxblocks | 367555.6 KBps | 222867.7 KBps File Copy 4096 bufsize 8000 maxblocks | 3675649.7 KBps | 1780614.4 KBps Pipe Throughput | 11872208.7 lps | 11855628.9 lps Pipe-based Context Switching | 1495126.5 lps | 1490533.9 lps Process Creation | 29881.2 lps | 28572.8 lps Shell Scripts (1 concurrent) | 23224.3 lpm | 22607.4 lpm Shell Scripts (8 concurrent) | 3531.4 lpm | 3211.9 lpm System Call Overhead | 10385653.0 lps | 10419979.0 lps Signed-off-by: Pan Xinhui Signed-off-by: Peter Zijlstra (Intel) Acked-by: Paolo Bonzini Cc: David.Laight@ACULAB.COM Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: benh@kernel.crashing.org Cc: boqun.feng@gmail.com Cc: borntraeger@de.ibm.com Cc: bsingharora@gmail.com Cc: dave@stgolabs.net Cc: jgross@suse.com Cc: kernellwp@gmail.com Cc: konrad.wilk@oracle.com Cc: linuxppc-dev@lists.ozlabs.org Cc: mpe@ellerman.id.au Cc: paulmck@linux.vnet.ibm.com Cc: paulus@samba.org Cc: rkrcmar@redhat.com Cc: virtualization@lists.linux-foundation.org Cc: will.deacon@arm.com Cc: xen-devel-request@lists.xenproject.org Cc: xen-devel@lists.xenproject.org Link: http://lkml.kernel.org/r/1478077718-37424-10-git-send-email-xinhui.pan@linux.vnet.ibm.com Signed-off-by: Ingo Molnar --- arch/x86/kernel/kvm.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c index edbbfc8..0b48dd2 100644 --- a/arch/x86/kernel/kvm.c +++ b/arch/x86/kernel/kvm.c @@ -415,6 +415,15 @@ void kvm_disable_steal_time(void) wrmsr(MSR_KVM_STEAL_TIME, 0, 0); } +static bool kvm_vcpu_is_preempted(int cpu) +{ + struct kvm_steal_time *src; + + src = &per_cpu(steal_time, cpu); + + return !!src->preempted; +} + #ifdef CONFIG_SMP static void __init kvm_smp_prepare_boot_cpu(void) { @@ -471,6 +480,9 @@ void __init kvm_guest_init(void) if (kvm_para_has_feature(KVM_FEATURE_STEAL_TIME)) { has_steal_clock = 1; pv_time_ops.steal_clock = kvm_steal_clock; +#ifdef CONFIG_PARAVIRT_SPINLOCKS + pv_lock_ops.vcpu_is_preempted = kvm_vcpu_is_preempted; +#endif } if (kvm_para_has_feature(KVM_FEATURE_PV_EOI))