From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-10.0 required=3.0 tests=INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id AA867C433FF for ; Fri, 2 Aug 2019 10:37:54 +0000 (UTC) Received: from mm01.cs.columbia.edu (mm01.cs.columbia.edu [128.59.11.253]) by mail.kernel.org (Postfix) with ESMTP id 6FDF82086A for ; Fri, 2 Aug 2019 10:37:54 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6FDF82086A Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvmarm-bounces@lists.cs.columbia.edu Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 275464A4CD; Fri, 2 Aug 2019 06:37:54 -0400 (EDT) X-Virus-Scanned: at lists.cs.columbia.edu Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id GblYU+Z9DJwM; Fri, 2 Aug 2019 06:37:52 -0400 (EDT) Received: from mm01.cs.columbia.edu (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 6C9BA4A549; Fri, 2 Aug 2019 06:37:51 -0400 (EDT) Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 60A184A51B for ; Fri, 2 Aug 2019 06:37:50 -0400 (EDT) X-Virus-Scanned: at lists.cs.columbia.edu Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id I0E6E8l+mBbm for ; Fri, 2 Aug 2019 06:37:49 -0400 (EDT) Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 657F84A555 for ; Fri, 2 Aug 2019 06:37:48 -0400 (EDT) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 2618B1596; Fri, 2 Aug 2019 03:37:48 -0700 (PDT) Received: from filthy-habits.cambridge.arm.com (filthy-habits.cambridge.arm.com [10.1.197.61]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id C51263F71F; Fri, 2 Aug 2019 03:37:46 -0700 (PDT) From: Marc Zyngier To: Paolo Bonzini , =?UTF-8?q?Radim=20Kr=C4=8Dm=C3=A1=C5=99?= , Julien Thierry , Suzuki K Poulose , James Morse , Joerg Roedel , Suravee Suthikulpanit , Tangnianyao Subject: [PATCH 2/2] KVM: Call kvm_arch_vcpu_blocking early into the blocking sequence Date: Fri, 2 Aug 2019 11:37:09 +0100 Message-Id: <20190802103709.70148-3-maz@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190802103709.70148-1-maz@kernel.org> References: <20190802103709.70148-1-maz@kernel.org> MIME-Version: 1.0 Cc: kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org X-BeenThere: kvmarm@lists.cs.columbia.edu X-Mailman-Version: 2.1.14 Precedence: list List-Id: Where KVM/ARM decisions are made List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu When a vpcu is about to block by calling kvm_vcpu_block, we call back into the arch code to allow any form of synchronization that may be required at this point (SVN stops the AVIC, ARM synchronises the VMCR and enables GICv4 doorbells). But this synchronization comes in quite late, as we've potentially waited for halt_poll_ns to expire. Instead, let's move kvm_arch_vcpu_blocking() to the beginning of kvm_vcpu_block(), which on ARM has several benefits: - VMCR gets synchronised early, meaning that any interrupt delivered during the polling window will be evaluated with the correct guest PMR - GICv4 doorbells are enabled, which means that any guest interrupt directly injected during that window will be immediately recognised Tang Nianyao ran some tests on a GICv4 machine to evaluate such change, and reported up to a 10% improvement for netperf: netperf result: D06 as server, intel 8180 server as client with change: package 512 bytes - 5500 Mbits/s package 64 bytes - 760 Mbits/s without change: package 512 bytes - 5000 Mbits/s package 64 bytes - 710 Mbits/s Signed-off-by: Marc Zyngier --- virt/kvm/kvm_main.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 887f3b0c2b60..90d429c703cb 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -2322,6 +2322,8 @@ void kvm_vcpu_block(struct kvm_vcpu *vcpu) bool waited = false; u64 block_ns; + kvm_arch_vcpu_blocking(vcpu); + start = cur = ktime_get(); if (vcpu->halt_poll_ns && !kvm_arch_no_poll(vcpu)) { ktime_t stop = ktime_add_ns(ktime_get(), vcpu->halt_poll_ns); @@ -2342,8 +2344,6 @@ void kvm_vcpu_block(struct kvm_vcpu *vcpu) } while (single_task_running() && ktime_before(cur, stop)); } - kvm_arch_vcpu_blocking(vcpu); - for (;;) { prepare_to_swait_exclusive(&vcpu->wq, &wait, TASK_INTERRUPTIBLE); @@ -2356,9 +2356,8 @@ void kvm_vcpu_block(struct kvm_vcpu *vcpu) finish_swait(&vcpu->wq, &wait); cur = ktime_get(); - - kvm_arch_vcpu_unblocking(vcpu); out: + kvm_arch_vcpu_unblocking(vcpu); block_ns = ktime_to_ns(cur) - ktime_to_ns(start); if (!vcpu_valid_wakeup(vcpu)) -- 2.20.1 _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm