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=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, 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 BFAA0C04AAC for ; Mon, 20 May 2019 13:03:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 959DB213F2 for ; Mon, 20 May 2019 13:03:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731409AbfETNDP (ORCPT ); Mon, 20 May 2019 09:03:15 -0400 Received: from mail-wr1-f50.google.com ([209.85.221.50]:34389 "EHLO mail-wr1-f50.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730506AbfETNDO (ORCPT ); Mon, 20 May 2019 09:03:14 -0400 Received: by mail-wr1-f50.google.com with SMTP id f8so8118055wrt.1 for ; Mon, 20 May 2019 06:03:14 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=EBtu0kPVDPNqfoCk67LhqasrzxQ+hshLRECRuXHeL70=; b=EegKiL5KZx+S67/q2+9Ixi6FYlZgxi6fzeb5vzNwU4W2ZA4hBHI/qQtRUw2NUkU0wL PqbseGLW+dBiTCGyTMh7Lv210N3s+TSQlWqjjpDbQoV6cCmh4hgNsCBlRy2xB4N/+93a stBNehDKM3gCPb0X5td5LQhx4TaUCzIZt9bf1/P0UK9kdO2wZH128LgTBkxffOLF0wQF F2oLtsUGfl4WTRhFVYOIOmNLBD0BQjCZsNHs5My+zGb/ZJRKFh92cf0gsKPPfX2gOyW6 kLmBimT49wrki6HV7IqzJNxZSiD0pW/6qWBOjgL/rHAytLZq6Jpj/d5/ZHfxGp0ewRwY mJow== X-Gm-Message-State: APjAAAXLGZw8QO6K1HqYhh9eNG9hTDL2w8cjvhMW2VIKDu0AU6gIhcOK cArZzqvMYXRSPuUe2W4GYaICqQ== X-Google-Smtp-Source: APXvYqxlKJc+iUvRpyjiosiwyPtlmi7VRgY3lWLVYukOSTDRh1LbA6BHR+K0oaUwJMV2TuQzCbIFhw== X-Received: by 2002:adf:e2c7:: with SMTP id d7mr9488238wrj.272.1558357393380; Mon, 20 May 2019 06:03:13 -0700 (PDT) Received: from ?IPv6:2001:b07:6468:f312:ac04:eef9:b257:b844? ([2001:b07:6468:f312:ac04:eef9:b257:b844]) by smtp.gmail.com with ESMTPSA id s127sm18174505wmf.48.2019.05.20.06.03.12 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 20 May 2019 06:03:12 -0700 (PDT) Subject: Re: [PATCH] KVM: lapic: Reuse auto-adjusted timer advance of first stable vCPU To: Sean Christopherson , =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= Cc: kvm@vger.kernel.org, Wanpeng Li References: <20190508214702.25317-1-sean.j.christopherson@intel.com> From: Paolo Bonzini Message-ID: <3ea5ae51-89b2-ee0c-d156-88198af90b95@redhat.com> Date: Mon, 20 May 2019 15:03:10 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 MIME-Version: 1.0 In-Reply-To: <20190508214702.25317-1-sean.j.christopherson@intel.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On 08/05/19 23:47, Sean Christopherson wrote: > + > + /* > + * The first vCPU to get a stable advancement time "wins" and > + * sets the advancement time that is used for *new* vCPUS that > + * are created with auto-adjusting enabled. > + */ > + if (apic->lapic_timer.timer_advance_adjust_done) > + (void)cmpxchg(&adjusted_timer_advance_ns, -1, > + timer_advance_ns); This is relatively expensive, so it should only be done after setting timer_advance_adjust_done to true. Paolo