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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 40E2BC31E40 for ; Fri, 9 Aug 2019 10:24:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1E4E72166E for ; Fri, 9 Aug 2019 10:24:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2406410AbfHIKYM (ORCPT ); Fri, 9 Aug 2019 06:24:12 -0400 Received: from mail-wr1-f68.google.com ([209.85.221.68]:33811 "EHLO mail-wr1-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726255AbfHIKYM (ORCPT ); Fri, 9 Aug 2019 06:24:12 -0400 Received: by mail-wr1-f68.google.com with SMTP id 31so97781582wrm.1 for ; Fri, 09 Aug 2019 03:24:10 -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:openpgp:message-id :date:user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=TRs9/vnl2x2fSDyEARf9rQa4tsoVDu7LpU0anhH+GLg=; b=Amog/8v9JziCSpkaV4yN8bfEfDQUsErMmObe0d0cHNZFgBTGctJqbjgoRQvRlDGpcS uIB7h1i8x3Zl9UQI4Jms85ziej2Igo6gvD4WBNk6vCb4KOYR4KHOvyftDsQN1NBsj7v+ Ai16/jMt8L3BkBrJXvybBSTyQzdasXaQmRANEnxwBQRnzNeYffsKowgs5hF+z+hiV9My MEOh+S//EEAy3+88YaNhopeapKVy5/fVZa+L0GDCqdVZ5crR+enjY8TliVWuSvVUhRBI 5dusLsfaIZI/rdroP947J3M5eNELNGvsxYGqFrmcS5CC2vtqX/vvi7TP6FV40cz6Ni1F cenQ== X-Gm-Message-State: APjAAAW4DObqL/iims3WW/tbu4nttBjRsl/MA7zeZlaNoBDKfWJjiT0r EcmweKgRccgqxaJtsKsbz1zqEg== X-Google-Smtp-Source: APXvYqx+uVkNssaIPX1SaKsQj+Z2Ktk1Buf8b3UqK4gB/0g65Hj8oHdWFOkI3Ei7n/L7LZzoAnP6iw== X-Received: by 2002:a5d:4a45:: with SMTP id v5mr15381943wrs.108.1565346250170; Fri, 09 Aug 2019 03:24:10 -0700 (PDT) Received: from [192.168.10.150] ([93.56.166.5]) by smtp.gmail.com with ESMTPSA id l25sm5040146wme.13.2019.08.09.03.24.09 (version=TLS1_3 cipher=AEAD-AES128-GCM-SHA256 bits=128/128); Fri, 09 Aug 2019 03:24:09 -0700 (PDT) Subject: Re: [PATCH] KVM: LAPIC: Periodically revaluate appropriate lapic_timer_advance_ns To: Wanpeng Li , linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= References: <1565329531-12327-1-git-send-email-wanpengli@tencent.com> From: Paolo Bonzini Openpgp: preference=signencrypt Message-ID: Date: Fri, 9 Aug 2019 12:24:08 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <1565329531-12327-1-git-send-email-wanpengli@tencent.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 09/08/19 07:45, Wanpeng Li wrote: > From: Wanpeng Li > > Even if for realtime CPUs, cache line bounces, frequency scaling, presence > of higher-priority RT tasks, etc can cause different response. These > interferences should be considered and periodically revaluate whether > or not the lapic_timer_advance_ns value is the best, do nothing if it is, > otherwise recaluate again. How much fluctuation do you observe between different runs? Paolo