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 19B98C433E0 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 C838E65101 for ; Tue, 9 Mar 2021 23:43:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232208AbhCIXmq (ORCPT ); Tue, 9 Mar 2021 18:42:46 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37566 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232199AbhCIXmW (ORCPT ); Tue, 9 Mar 2021 18:42:22 -0500 Received: from mail-pl1-x62b.google.com (mail-pl1-x62b.google.com [IPv6:2607:f8b0:4864:20::62b]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BD55CC06175F for ; Tue, 9 Mar 2021 15:42:22 -0800 (PST) Received: by mail-pl1-x62b.google.com with SMTP id u18so7516750plc.12 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=QiJmD8wLg7i8eyaSGz0a+QE/38nKe4dsXKQmfM+0xGASactYFgcC24hbyhnIeOhHQX je8AXzaLToPZgQ7SJguR+Wl//CMo/3YRIDlcnzps5YBwv2jR7eJ7o/KgLoTH5eO+VmmZ 7R0yOEEndjmINFbzzY8RXyePffu+sM92j0g74EZJ2VLDNajZASOpJX3S/QBblkapKUPm jHcO6EOHi3E8uAsYBBe/dotQKEEo+VbFyYs27Tvah8jzv8HhSvet4lhp3wMIT44NtjWa uV7S88WrnUHFv74M75tZJ+JPf2cHQcvladCnNR9q37zJWw7HUvkigesvcsJy7sxPwL51 qq2g== X-Gm-Message-State: AOAM532LvoIXj3dS42tNv7yJ31Z8Q0Q4Lwx1Z4pt1wp+Pd9LgsN3OAnm 5xIaiwjiCqz761qtLOrtLepFng== 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: kvm@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.