From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934004AbcLTJcT (ORCPT ); Tue, 20 Dec 2016 04:32:19 -0500 Received: from mx1.redhat.com ([209.132.183.28]:50346 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933260AbcLTJcQ (ORCPT ); Tue, 20 Dec 2016 04:32:16 -0500 Subject: Re: [PATCH 1/6] KVM: x86: add VCPU stat for KVM_REQ_EVENT processing To: Roman Kagan , linux-kernel@vger.kernel.org, kvm@vger.kernel.org, rkrcmar@redhat.com, dplotnikov@virtuozzo.com References: <1482140838-6303-1-git-send-email-pbonzini@redhat.com> <1482140838-6303-2-git-send-email-pbonzini@redhat.com> <20161220092101.GE2081@rkaganb.sw.ru> From: Paolo Bonzini Message-ID: <2bff3865-f731-c504-08be-5473db61b0c6@redhat.com> Date: Tue, 20 Dec 2016 10:32:13 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.5.1 MIME-Version: 1.0 In-Reply-To: <20161220092101.GE2081@rkaganb.sw.ru> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.30]); Tue, 20 Dec 2016 09:32:16 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 20/12/2016 10:21, Roman Kagan wrote: > On Mon, Dec 19, 2016 at 10:47:13AM +0100, Paolo Bonzini wrote: >> Signed-off-by: Paolo Bonzini >> --- >> arch/x86/include/asm/kvm_host.h | 1 + >> arch/x86/kvm/x86.c | 2 ++ >> 2 files changed, 3 insertions(+) >> >> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h >> index 994d8ed9fc6c..08cfd45a9452 100644 >> --- a/arch/x86/include/asm/kvm_host.h >> +++ b/arch/x86/include/asm/kvm_host.h >> @@ -850,6 +850,7 @@ struct kvm_vcpu_stat { >> u64 hypercalls; >> u64 irq_injections; >> u64 nmi_injections; >> + u64 req_event; >> }; >> >> struct x86_instruction_info; >> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c >> index e95d94edbdc3..e9b512090865 100644 >> --- a/arch/x86/kvm/x86.c >> +++ b/arch/x86/kvm/x86.c >> @@ -180,6 +180,7 @@ struct kvm_stats_debugfs_item debugfs_entries[] = { >> { "insn_emulation_fail", VCPU_STAT(insn_emulation_fail) }, >> { "irq_injections", VCPU_STAT(irq_injections) }, >> { "nmi_injections", VCPU_STAT(nmi_injections) }, >> + { "req_event", VCPU_STAT(req_event) }, >> { "mmu_shadow_zapped", VM_STAT(mmu_shadow_zapped) }, >> { "mmu_pte_write", VM_STAT(mmu_pte_write) }, >> { "mmu_pte_updated", VM_STAT(mmu_pte_updated) }, >> @@ -6691,6 +6692,7 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu) >> } >> >> if (kvm_check_request(KVM_REQ_EVENT, vcpu) || req_int_win) { >> + ++vcpu->stat.req_event; >> kvm_apic_accept_events(vcpu); >> if (vcpu->arch.mp_state == KVM_MP_STATE_INIT_RECEIVED) { >> r = 1; > > Just curious what kind of information you expect to be able to extract > from this counter? I mean, I'm not opposed to introducing it, I just > want to figure out how to use it properly. Compare against > irq_injections? Yes, exactly. Since vmexit cycle counts are always a bit noisy, I could compare irq_injections against req_event and get an idea of the expected improvement. Also for example the stat shows that the sti_hlt case has a higher # of req_event than sti_nop. I have a patch to fix that, but it's left for later because I don't know of a workload that triggers it. I don't really need this patch of course. > Also I guess it may be interesting to count branching to > cancel_injection label in vcpu_enter_guest. Interesting one too. Paolo