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=-13.3 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_IN_DEF_DKIM_WL 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 7508FC4332E for ; Tue, 9 Mar 2021 23:43:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 54A53650B4 for ; Tue, 9 Mar 2021 23:43:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232214AbhCIXmq (ORCPT ); Tue, 9 Mar 2021 18:42:46 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37564 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232200AbhCIXmW (ORCPT ); Tue, 9 Mar 2021 18:42:22 -0500 Received: from mail-pj1-x1033.google.com (mail-pj1-x1033.google.com [IPv6:2607:f8b0:4864:20::1033]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BC925C06174A for ; Tue, 9 Mar 2021 15:42:22 -0800 (PST) Received: by mail-pj1-x1033.google.com with SMTP id q6-20020a17090a4306b02900c42a012202so6426299pjg.5 for ; Tue, 09 Mar 2021 15:42:22 -0800 (PST) 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=0wvDPTdhCRY4Owyf+IK6ksYfroTUCgYzibiZjp0ODqY=; b=r7jK6uQGSxTFfVJLaJqJiXaP6p+mNOlP9yG/+PDhRucxgePEuLoOvAxEfa1fYCGIDB d3VX9WbfSaS3wtY3PnODKlgekVbUM2a8zVR6patUtz43Bu3dMA99u8n5CT2KCTiNL+0B +Wd/4ebvJv5/chhT7ArCsgq1gD/GEbIf8VX/EO47D5DAgcLEKYuvX9mtm9KdJESK0FUK hFGhwTG84Fsoo0QEK9P5SA3nvVWK0VSX0opharoHrFO9TLYoF8Spxz0b1JE3wHMz2pka o/rPJurVUIMZ6vISquW8yRmxrG5MCxg/BeDxejn67Oo+ebfn7me3p9TLxFHDAdA45tYh jELQ== 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=0wvDPTdhCRY4Owyf+IK6ksYfroTUCgYzibiZjp0ODqY=; b=cIb+lSSSdk1IJqkyhsMLEBF49cjycjdWmFOrYXfdejo2dKz+cdCKa7awxHwsRwcXyQ RPsamvTa7HDQRcjOQbjaj/2wkLgaVQ6RV/3M/8zj6A9OFl9InZJ2Kg5KgBBzMrCfGSsj YSXc9DHy1kphNCya4y0C5mZfc+5BqwnCr/5+3jGZVnv9tQh15AAV5RAXSZzUYnJ01o2s XceS2pLJNQNKkUdArcANDs1Oattl3OhyEt4MCYAklStQ8/iy0dnISTHzsMQ43wF1bnTH 2w5o3qba+0WO/bjQgMyQWuGloskSDl04fnxhgApRw0q6OPbpXQO9Lvhqmf4kpONnEwbO 2sNQ== X-Gm-Message-State: AOAM533PBvFA9Mu4W97c3EUhVOFd/4ZwGY6ToyQ41Ox0phV9RTRo7+Jk U4H6JkhDhcZ7FSt5AlalXtDJcvcHKa5fEQ== X-Google-Smtp-Source: ABdhPJwXvMwK7qJH+rWBZr7Qk9TAHNVGCYBEQR+Mt9d8D0+yNsfzy7aeckKFYMnJ0j7XzEQQsXWOiQ== X-Received: by 2002:a17:902:b7c5:b029:e6:1a9f:5f55 with SMTP id v5-20020a170902b7c5b02900e61a9f5f55mr176648plz.57.1615333342173; Tue, 09 Mar 2021 15:42:22 -0800 (PST) Received: from google.com ([2620:15c:f:10:e4dd:6c31:9463:f8da]) by smtp.gmail.com with ESMTPSA id 68sm14247434pfd.75.2021.03.09.15.42.20 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 09 Mar 2021 15:42:21 -0800 (PST) Date: Tue, 9 Mar 2021 15:42:15 -0800 From: Sean Christopherson To: Haiwei Li Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org, pbonzini@redhat.com, vkuznets@redhat.com, wanpengli@tencent.com, jmattson@google.com, joro@8bytes.org, Haiwei Li Subject: Re: [PATCH] kvm: lapic: add module parameters for LAPIC_TIMER_ADVANCE_ADJUST_MAX/MIN Message-ID: References: <20210303020946.26083-1-lihaiwei.kernel@gmail.com> <03239d81-df56-a6c9-c79d-c14d22f62705@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <03239d81-df56-a6c9-c79d-c14d22f62705@gmail.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Mar 03, 2021, Haiwei Li wrote: > On 21/3/3 10:09, lihaiwei.kernel@gmail.com wrote: > > From: Haiwei Li > > > > In my test environment, advance_expire_delta is frequently greater than > > the fixed LAPIC_TIMER_ADVANCE_ADJUST_MAX. And this will hinder the > > adjustment. > > Supplementary details: > > I have tried to backport timer related features to our production > kernel. > > After completed, i found that advance_expire_delta is frequently greater > than the fixed value. It's necessary to trun the fixed to dynamically > values. Does this reproduce on an upstream kernel? If so... 1. How much over the 10k cycle limit is the delta? 2. Any idea what causes the large delta? E.g. is there something that can and/or should be fixed elsewhere? 3. Is it platform/CPU specific? Ideally, KVM would play nice with "all" environments by default without forcing the admin to hand-tune things.