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=-18.3 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_IN_DEF_DKIM_WL 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 63DCAC43460 for ; Tue, 18 May 2021 19:14:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 48A5860724 for ; Tue, 18 May 2021 19:14:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1351745AbhERTPW (ORCPT ); Tue, 18 May 2021 15:15:22 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35400 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S243096AbhERTPV (ORCPT ); Tue, 18 May 2021 15:15:21 -0400 Received: from mail-pl1-x629.google.com (mail-pl1-x629.google.com [IPv6:2607:f8b0:4864:20::629]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D3075C061573 for ; Tue, 18 May 2021 12:14:02 -0700 (PDT) Received: by mail-pl1-x629.google.com with SMTP id s20so5643336plr.13 for ; Tue, 18 May 2021 12:14:02 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=WnK4uajSuBCF+iu/8FjWrAQzpSy036uu06aeXXfdggs=; b=Fj+N4PhfIl7jv6LOEmmuwwPamlR3Z2YzG/LLmlR0QybVOTTn2vyDdSUMTTagMgBNV+ Zm30YA60fRu72DnMhpG6DVO6vbcxSzXEKSqFTSCPWR7hHWEyjiY15OtF153VplUIesO6 4Fy4Qz7mrNf0qBDERWZUVjI78VZXfShNl3AAM5g0mnwkbSYtSLOPwyxwkC9PEkw8OA2P r5e7R56Yvpg8VN6/VlNGT+jeCxaFQy5h0jr6jrIc0KL8+9iUmn3Cypq2hgfbc+lGxRxH hgfzqm08H00oNE9YvPk0mP/SnPNZJbzWFSrCpIAt3L+C3BV2PVVi8Xm2tHbFZMadNSN1 cGdg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=WnK4uajSuBCF+iu/8FjWrAQzpSy036uu06aeXXfdggs=; b=Aj5z/d27HC10pug3s+dH+bD/LRDycEzsj97nRhwuU5jD7z+/G28VUk1GkBnwOzWIfL 1myjxltQNsb7ZjF0M8dvP0JV2GAMHbwKpr8YVNWiAWItwqCwsM4GrVUWHK5QLzPeqaah E7Gedu//Uyy2miTN4WZDH2UvSgplzdp/HhG68ddQv2eqGbjdBPLmKXoYFUZN2nz+wnnx hMNnl/1KqyCVv7SfYkCgBSs0yvx13LXr02qbnHUxH9S8gV1ucuRuMld6XuFKhfFtesyY 3v/FIAmdWiVZgvcwGRvYiy/Z3mPs63efo7wP4r5tbmZHqLfuBj9+5chSmRqy3U+jgU7c T3dQ== X-Gm-Message-State: AOAM530q5rzykhzm0i+99uWjHU+MbBbwAMZ2B3/mB0TmsDOazFdTUfTi ua3ZmMEABrYKBCAapsPwbAGgMZrPRDOUKg== X-Google-Smtp-Source: ABdhPJzlwjf30kWQb8nqUSwMKzmhMqzQ9xOMZbWixVKBohtjcV94vQCRIoWVsR2MNR3qYrJlDw4b1Q== X-Received: by 2002:a17:902:34f:b029:ef:3d14:1c27 with SMTP id 73-20020a170902034fb02900ef3d141c27mr6296909pld.65.1621365242262; Tue, 18 May 2021 12:14:02 -0700 (PDT) Received: from google.com (240.111.247.35.bc.googleusercontent.com. [35.247.111.240]) by smtp.gmail.com with ESMTPSA id u23sm2943943pfn.106.2021.05.18.12.14.01 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 18 May 2021 12:14:01 -0700 (PDT) Date: Tue, 18 May 2021 19:13:58 +0000 From: Sean Christopherson To: Wanpeng Li Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org, Paolo Bonzini , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel Subject: Re: [PATCH v4 5/5] KVM: LAPIC: Narrow the timer latency between wait_lapic_expire and world switch Message-ID: References: <1621339235-11131-1-git-send-email-wanpengli@tencent.com> <1621339235-11131-5-git-send-email-wanpengli@tencent.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1621339235-11131-5-git-send-email-wanpengli@tencent.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, May 18, 2021, Wanpeng Li wrote: > From: Wanpeng Li > > Let's treat lapic_timer_advance_ns automatic tuning logic as hypervisor > overhead, move it before wait_lapic_expire instead of between wait_lapic_expire > and the world switch, the wait duration should be calculated by the > up-to-date guest_tsc after the overhead of automatic tuning logic. This > patch reduces ~30+ cycles for kvm-unit-tests/tscdeadline-latency when testing > busy waits. > > Signed-off-by: Wanpeng Li > --- Reviewed-by: Sean Christopherson