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=-16.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham 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 43604C4338F for ; Fri, 20 Aug 2021 12:44:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 25DD9610D2 for ; Fri, 20 Aug 2021 12:44:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240561AbhHTMop (ORCPT ); Fri, 20 Aug 2021 08:44:45 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:34089 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240505AbhHTMon (ORCPT ); Fri, 20 Aug 2021 08:44:43 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1629463444; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=Tv5qi40eLMbo4zSMM9UWSwuDMOHZ6NnJZ4bVmrBwXiE=; b=dtxHjb8ACXph9gF5FbJ9QFO4qGa3rWnb3w630Zuu5T54R+wUU388ZuhxZ8BIiRAaD7Ws2m QLBBJDHpoDk2d2aj0lUMK7k0aKfA56S3cMshwYJYLphCxVQAV7qrfXj/0piun1ahIOZpiQ dFZwjre9xiUDqZZCzGaoL/ruq7JeSOI= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-433-HYzNmTkGM_efCnKX-f_XAA-1; Fri, 20 Aug 2021 08:44:03 -0400 X-MC-Unique: HYzNmTkGM_efCnKX-f_XAA-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id DEEF4875054; Fri, 20 Aug 2021 12:44:01 +0000 (UTC) Received: from vitty.brq.redhat.com (unknown [10.40.194.44]) by smtp.corp.redhat.com (Postfix) with ESMTP id B5DD15C25D; Fri, 20 Aug 2021 12:43:55 +0000 (UTC) From: Vitaly Kuznetsov To: kvm@vger.kernel.org, Paolo Bonzini Cc: Sean Christopherson , Wanpeng Li , Jim Mattson , "Dr. David Alan Gilbert" , Nitesh Narayan Lal , linux-kernel@vger.kernel.org Subject: [PATCH 1/2] KVM: Optimize kvm_make_vcpus_request_mask() a bit Date: Fri, 20 Aug 2021 14:43:53 +0200 Message-Id: <20210820124354.582222-1-vkuznets@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Iterating over set bits in 'vcpu_bitmap' should be faster than going through all vCPUs, especially when just a few bits are set. Signed-off-by: Vitaly Kuznetsov --- virt/kvm/kvm_main.c | 49 +++++++++++++++++++++++++++++---------------- 1 file changed, 32 insertions(+), 17 deletions(-) diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 3e67c93ca403..0f873c5ed538 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -257,34 +257,49 @@ static inline bool kvm_kick_many_cpus(const struct cpumask *cpus, bool wait) return true; } +static void kvm_make_vcpu_request(struct kvm *kvm, struct kvm_vcpu *vcpu, + unsigned int req, cpumask_var_t tmp) +{ + int cpu = vcpu->cpu; + + kvm_make_request(req, vcpu); + + if (!(req & KVM_REQUEST_NO_WAKEUP) && kvm_vcpu_wake_up(vcpu)) + return; + + if (tmp != NULL && cpu != -1 && cpu != raw_smp_processor_id() && + kvm_request_needs_ipi(vcpu, req)) + __cpumask_set_cpu(cpu, tmp); +} + bool kvm_make_vcpus_request_mask(struct kvm *kvm, unsigned int req, struct kvm_vcpu *except, unsigned long *vcpu_bitmap, cpumask_var_t tmp) { - int i, cpu, me; + int i; struct kvm_vcpu *vcpu; bool called; - me = get_cpu(); - - kvm_for_each_vcpu(i, vcpu, kvm) { - if ((vcpu_bitmap && !test_bit(i, vcpu_bitmap)) || - vcpu == except) - continue; - - kvm_make_request(req, vcpu); - cpu = vcpu->cpu; - - if (!(req & KVM_REQUEST_NO_WAKEUP) && kvm_vcpu_wake_up(vcpu)) - continue; + preempt_disable(); - if (tmp != NULL && cpu != -1 && cpu != me && - kvm_request_needs_ipi(vcpu, req)) - __cpumask_set_cpu(cpu, tmp); + if (likely(vcpu_bitmap)) { + for_each_set_bit(i, vcpu_bitmap, KVM_MAX_VCPUS) { + vcpu = kvm_get_vcpu(kvm, i); + if (!vcpu || vcpu == except) + continue; + kvm_make_vcpu_request(kvm, vcpu, req, tmp); + } + } else { + kvm_for_each_vcpu(i, vcpu, kvm) { + if (vcpu == except) + continue; + kvm_make_vcpu_request(kvm, vcpu, req, tmp); + } } called = kvm_kick_many_cpus(tmp, !!(req & KVM_REQUEST_WAIT)); - put_cpu(); + + preempt_enable(); return called; } -- 2.31.1