From patchwork Mon May 18 08:44:04 2009 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Gleb Natapov X-Patchwork-Id: 24418 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 n4I8igtL023005 for ; Mon, 18 May 2009 08:44:43 GMT Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754776AbZERIoN (ORCPT ); Mon, 18 May 2009 04:44:13 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750779AbZERIoM (ORCPT ); Mon, 18 May 2009 04:44:12 -0400 Received: from mx2.redhat.com ([66.187.237.31]:44435 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754083AbZERIoJ (ORCPT ); Mon, 18 May 2009 04:44:09 -0400 Received: from int-mx2.corp.redhat.com (int-mx2.corp.redhat.com [172.16.27.26]) by mx2.redhat.com (8.13.8/8.13.8) with ESMTP id n4I8i9kp006892 for ; Mon, 18 May 2009 04:44:09 -0400 Received: from ns3.rdu.redhat.com (ns3.rdu.redhat.com [10.11.255.199]) by int-mx2.corp.redhat.com (8.13.1/8.13.1) with ESMTP id n4I8i86q026969; Mon, 18 May 2009 04:44:08 -0400 Received: from dhcp-1-237.tlv.redhat.com (dhcp-1-237.tlv.redhat.com [10.35.1.237]) by ns3.rdu.redhat.com (8.13.8/8.13.8) with ESMTP id n4I8i7f0008267; Mon, 18 May 2009 04:44:07 -0400 Received: by dhcp-1-237.tlv.redhat.com (Postfix, from userid 13519) id 0136A18D463; Mon, 18 May 2009 11:44:06 +0300 (IDT) From: Gleb Natapov To: avi@redhat.com Cc: kvm@vger.kernel.org Subject: [PATCH] [APIC] Optimize searching for highest IRR Date: Mon, 18 May 2009 11:44:04 +0300 Message-Id: <1242636246-11547-1-git-send-email-gleb@redhat.com> X-Scanned-By: MIMEDefang 2.58 on 172.16.27.26 Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org Most of the time IRR is empty, so instead of scanning the whole IRR on each VM entry keep a variable that tells us if IRR is not empty. IRR will have to be scanned twice on each IRQ delivery, but this is much more rare than VM entry. Signed-off-by: Gleb Natapov --- arch/x86/kvm/lapic.c | 19 ++++++++++++++++--- arch/x86/kvm/lapic.h | 1 + 2 files changed, 17 insertions(+), 3 deletions(-) diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c index ae99d83..2c25b07 100644 --- a/arch/x86/kvm/lapic.c +++ b/arch/x86/kvm/lapic.c @@ -165,24 +165,36 @@ static int find_highest_vector(void *bitmap) static inline int apic_test_and_set_irr(int vec, struct kvm_lapic *apic) { + apic->irr_pending = true; return apic_test_and_set_vector(vec, apic->regs + APIC_IRR); } -static inline void apic_clear_irr(int vec, struct kvm_lapic *apic) +static inline int apic_search_irr(struct kvm_lapic *apic) { - apic_clear_vector(vec, apic->regs + APIC_IRR); + return find_highest_vector(apic->regs + APIC_IRR); } static inline int apic_find_highest_irr(struct kvm_lapic *apic) { int result; - result = find_highest_vector(apic->regs + APIC_IRR); + if (!apic->irr_pending) + return -1; + + result = apic_search_irr(apic); ASSERT(result == -1 || result >= 16); return result; } +static inline void apic_clear_irr(int vec, struct kvm_lapic *apic) +{ + apic->irr_pending = false; + apic_clear_vector(vec, apic->regs + APIC_IRR); + if (apic_search_irr(apic) != -1) + apic->irr_pending = true; +} + int kvm_lapic_find_highest_irr(struct kvm_vcpu *vcpu) { struct kvm_lapic *apic = vcpu->arch.apic; @@ -842,6 +854,7 @@ void kvm_lapic_reset(struct kvm_vcpu *vcpu) apic_set_reg(apic, APIC_ISR + 0x10 * i, 0); apic_set_reg(apic, APIC_TMR + 0x10 * i, 0); } + apic->irr_pending = false; update_divide_count(apic); atomic_set(&apic->lapic_timer.pending, 0); if (vcpu->vcpu_id == 0) diff --git a/arch/x86/kvm/lapic.h b/arch/x86/kvm/lapic.h index a587f83..3f3ecc6 100644 --- a/arch/x86/kvm/lapic.h +++ b/arch/x86/kvm/lapic.h @@ -12,6 +12,7 @@ struct kvm_lapic { struct kvm_timer lapic_timer; u32 divide_count; struct kvm_vcpu *vcpu; + bool irr_pending; struct page *regs_page; void *regs; gpa_t vapic_addr;