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=-0.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=no 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 7CB5CC34045 for ; Tue, 18 Feb 2020 16:29:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 55CCB2464E for ; Tue, 18 Feb 2020 16:29:52 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="cO47Is+h" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726707AbgBRQ3v (ORCPT ); Tue, 18 Feb 2020 11:29:51 -0500 Received: from us-smtp-2.mimecast.com ([207.211.31.81]:59079 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726422AbgBRQ3u (ORCPT ); Tue, 18 Feb 2020 11:29:50 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1582043389; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=/xeFn2xogkvVTbJnDqLCWor5PNlBtKum0AFBL80A1+Q=; b=cO47Is+hcCu1c5DYa7K1krdGrOf7LOS1FBQO5Pr4XDINCZ3kcT/6gxr5tufh+k4Rm3HEEN HGjIcDiqo5ySDpQlNOwQNmbWOcjy12IB0o7e+AIxp9uSGn3EUvVLAa3RRMsT44e2rl6wgP EwYS8SbjS7m3LitfgGxon5qfxT03MIw= Received: from mail-wm1-f71.google.com (mail-wm1-f71.google.com [209.85.128.71]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-209-IHskR0TJPmenkVWzUSfg6g-1; Tue, 18 Feb 2020 11:29:47 -0500 X-MC-Unique: IHskR0TJPmenkVWzUSfg6g-1 Received: by mail-wm1-f71.google.com with SMTP id f207so262755wme.6 for ; Tue, 18 Feb 2020 08:29:47 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:in-reply-to:references:date :message-id:mime-version; bh=/xeFn2xogkvVTbJnDqLCWor5PNlBtKum0AFBL80A1+Q=; b=IS/8psNJbILaW60bcDD8UizqPgT3Fmam+5NrtKDIjQiVrc6oa4OvqZIuN3KrleBH7R s8hTcZ0IhLQwwpmS1MZkxepl60V0F3X0dVfvSB8Q54EffhiNoiovGpFvbb49LP4B1XRv NL1L6On+LFi3gBSjfz5JjpMcXisLgiJ0/q3dsurMtO6wfRbxYCWFkO7DPt5R7H5k70HH nnebGQEoNmNS2NjLNiOkFe9xM6bUtOczMILIb4PzXt1ciAlWY+KApJta5x1DuHRpFo8S 4opLhUnCqlAA7ZXdEIH0PDXqAcsszBrr1UUyPxzqu2lA7WGWvbpuLIXa3s8OBXN9wGet nYDA== X-Gm-Message-State: APjAAAUf+OZvHTsrBaa0dSQgxVB56mYTbuTIuBrD7B+7MANQ348+iTvD im3UwzgCACFIZedvq5+8N7ke9HccGaQLtGbvMnKyOvbgioUpvPliWPD8eQ+Z407U8ulkUePoOQP 3JZyGxBCrwKLKWMiZ7L48AEOL X-Received: by 2002:a05:600c:21c5:: with SMTP id x5mr4126821wmj.72.1582043386465; Tue, 18 Feb 2020 08:29:46 -0800 (PST) X-Google-Smtp-Source: APXvYqyu+z4ptlYhKpFiduZBLAPpESjhfWuQywip8nwgL2XtTPQu1tJhUCSKUdBT0QweLYw1Oz5CRg== X-Received: by 2002:a05:600c:21c5:: with SMTP id x5mr4126799wmj.72.1582043386211; Tue, 18 Feb 2020 08:29:46 -0800 (PST) Received: from vitty.brq.redhat.com (nat-pool-brq-t.redhat.com. [213.175.37.10]) by smtp.gmail.com with ESMTPSA id x6sm4088344wmi.44.2020.02.18.08.29.45 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 18 Feb 2020 08:29:45 -0800 (PST) From: Vitaly Kuznetsov To: Paolo Bonzini , Wanpeng Li Cc: Sean Christopherson , Wanpeng Li , Jim Mattson , Joerg Roedel , linux-kernel@vger.kernel.org, kvm@vger.kernel.org Subject: Re: [PATCH v4 1/2] KVM: X86: Less kvmclock sync induced vmexits after VM boots In-Reply-To: References: <1581988630-19182-1-git-send-email-wanpengli@tencent.com> <87r1ys7xpk.fsf@vitty.brq.redhat.com> Date: Tue, 18 Feb 2020 17:29:44 +0100 Message-ID: <87mu9f97uv.fsf@vitty.brq.redhat.com> MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Paolo Bonzini writes: > On 18/02/20 15:54, Vitaly Kuznetsov wrote: >>> - schedule_delayed_work(&kvm->arch.kvmclock_sync_work, >>> - KVMCLOCK_SYNC_PERIOD); >>> + if (vcpu->vcpu_idx == 0) >>> + schedule_delayed_work(&kvm->arch.kvmclock_sync_work, >>> + KVMCLOCK_SYNC_PERIOD); >>> } >>> >>> void kvm_arch_vcpu_destroy(struct kvm_vcpu *vcpu) >> Forgive me my ignorance, I was under the impression >> schedule_delayed_work() doesn't do anything if the work is already >> queued (see queue_delayed_work_on()) and we seem to be scheduling the >> same work (&kvm->arch.kvmclock_sync_work) which is per-kvm (not >> per-vcpu). > > No, it executes after 5 minutes. I agree that the patch shouldn't be > really necessary, though you do save on cacheline bouncing due to > test_and_set_bit. > True, but the changelog should probably be updated then. -- Vitaly