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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id DDF6ACD6115 for ; Wed, 11 Oct 2023 08:31:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230093AbjJKIbH (ORCPT ); Wed, 11 Oct 2023 04:31:07 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55480 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230366AbjJKIbB (ORCPT ); Wed, 11 Oct 2023 04:31:01 -0400 Received: from mail-oo1-xc30.google.com (mail-oo1-xc30.google.com [IPv6:2607:f8b0:4864:20::c30]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 429F4A7 for ; Wed, 11 Oct 2023 01:30:38 -0700 (PDT) Received: by mail-oo1-xc30.google.com with SMTP id 006d021491bc7-5812eaed1eeso1371752eaf.0 for ; Wed, 11 Oct 2023 01:30:38 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bytedance.com; s=google; t=1697013037; x=1697617837; darn=vger.kernel.org; h=content-transfer-encoding:in-reply-to:from:references:cc:to :content-language:subject:user-agent:mime-version:date:message-id :from:to:cc:subject:date:message-id:reply-to; bh=mXUNV0ujQSLE2qvD9KPcPTpmkRZtdqskCOFXDdWDov4=; b=EPLS26YSEhCoWSvtFoQnhL+tNDROcwhYKXyIpvHxjUzWvb+xTX31Odj1/cgxfNe+4k StcNwZ0pgba/et5THkLI9nbloAm2piGEUca8bgf4XR0ggjJ/dG5QDftlHr49LutLZNOL Oa1+N1ckewuT1U4HSDwznVbGyYpiDw3+vRI7KYcH4hn75BWjMVwpUrcFSKZ0pnYsMqKu hupMUIwURrMtldSSIWAdLJsi+M0FaBwU3CmV2HNpnmUe79An8Zyu70QSCyuUt90s8osl GJyJxA3DjDThzOEQN63r5Pd5QPnoC+EB7J2f9nbUVwzontrsDhHIHpDPNPOB0x+t1PIs GRbA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1697013037; x=1697617837; h=content-transfer-encoding:in-reply-to:from:references:cc:to :content-language:subject:user-agent:mime-version:date:message-id :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=mXUNV0ujQSLE2qvD9KPcPTpmkRZtdqskCOFXDdWDov4=; b=QRdZbXLrvWiUXsve5QQvSBilMnhmxFIFhqN9nKYS8CnbS6Uu3cTijRiQUxNIb4f0Fp XJHFi7YYkITN2bRT+Ld+17rbZytVBBP5j6cqhX9QxEuuqUdnmrGz0DFSrw41DtWzjSYD AqhnfrEKNijPBi3DIRv1u1J4VjO5EmYbUaVy564RHCVApD+yPFNHMtB44NU4SCQN/TcY 8P0SnsjASoPKpZM/sp0I/yCjEx9rqb7V9jdlTgm99OAf0Y/8pznFpY36qkQrWq91yDXW Jln8Yi8GJ/xIr/6EJF1FDlgpyk9o6Hk7uH60vn3gKV9rOIOq76vJI6EkihhxpeSkZSir WCYg== X-Gm-Message-State: AOJu0YwqYfVV0W9veFtzs8vMCIHAdY0gjFPCLXIujJG+Og7DfwfDlvXb 4enJjrwBjrmZ23vI3B3Mn49Oxw== X-Google-Smtp-Source: AGHT+IEnReR/IaHjXbz/+32O1iKTLaZhsq3RIRBueDldlWv0/NdJuStpE6Mc1cvGy7RpdO5WXFYFQw== X-Received: by 2002:a05:6358:988d:b0:14c:704b:d19f with SMTP id q13-20020a056358988d00b0014c704bd19fmr15511969rwa.3.1697013037515; Wed, 11 Oct 2023 01:30:37 -0700 (PDT) Received: from [10.84.153.115] ([203.208.167.147]) by smtp.gmail.com with ESMTPSA id r5-20020a62e405000000b006933b69f7afsm9540407pfh.42.2023.10.11.01.30.28 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 11 Oct 2023 01:30:36 -0700 (PDT) Message-ID: <3156c8fe-5488-4044-8282-79495bf89f6d@bytedance.com> Date: Wed, 11 Oct 2023 16:30:26 +0800 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: Re: [PATCH 01/15] sched/fair: Add avg_vruntime Content-Language: en-US To: Peter Zijlstra Cc: mingo@kernel.org, vincent.guittot@linaro.org, linux-kernel@vger.kernel.org, juri.lelli@redhat.com, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de, bristot@redhat.com, corbet@lwn.net, qyousef@layalina.io, chris.hyser@oracle.com, patrick.bellasi@matbug.net, pjt@google.com, pavel@ucw.cz, qperret@google.com, tim.c.chen@linux.intel.com, joshdon@google.com, timj@gnu.org, kprateek.nayak@amd.com, yu.c.chen@intel.com, youssefesmat@chromium.org, joel@joelfernandes.org, efault@gmx.de, tglx@linutronix.de References: <20230531115839.089944915@infradead.org> <20230531124603.654144274@infradead.org> <75adcb1a-c02f-4d7c-bd9c-ab4f403af3e8@bytedance.com> <20231011073001.GI14330@noisy.programming.kicks-ass.net> From: Abel Wu In-Reply-To: <20231011073001.GI14330@noisy.programming.kicks-ass.net> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 10/11/23 3:30 PM, Peter Zijlstra Wrote: > On Wed, Oct 11, 2023 at 12:15:28PM +0800, Abel Wu wrote: >> On 5/31/23 7:58 PM, Peter Zijlstra wrote: >>> +/* >>> + * Compute virtual time from the per-task service numbers: >>> + * >>> + * Fair schedulers conserve lag: >>> + * >>> + * \Sum lag_i = 0 >>> + * >>> + * Where lag_i is given by: >>> + * >>> + * lag_i = S - s_i = w_i * (V - v_i) >> >> Since the ideal service time S is task-specific, should this be: >> >> lag_i = S_i - s_i = w_i * (V - v_i) > > It is not, S is the same for all tasks. Remember, the base form is a > differential equation and all tasks progress at the same time at dt/w_i > while S progresses at dt/W. IIUC it's V progresses at dt/W and is same for all tasks, not S which is measured in real time (V*w_i).