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=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS 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 DB321C433E0 for ; Tue, 16 Mar 2021 09:43:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 99F6865010 for ; Tue, 16 Mar 2021 09:43:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234309AbhCPJmn (ORCPT ); Tue, 16 Mar 2021 05:42:43 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46052 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234516AbhCPJmT (ORCPT ); Tue, 16 Mar 2021 05:42:19 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D5E98C06174A for ; Tue, 16 Mar 2021 02:42:18 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=NDNqJ87ah9iwtWeelWRtR81DTZqzhakhgaGhPf9ZGZw=; b=Jh8cZ6/Dkjr2v7D+O6D8TPmGub kSnUSs3G8eM0PT2wxAgy/uSBzT00dMmXSuNG9W9szWBjKjntsqLPORebUcXU7jRsqY8VCW/Cv8PVI td+Ni377lKNBOTBMjMlcZjr1L3cVMYezYARQ993TpR6lqht0MuSUN0Co1iGIiUyq9t+Fb0dXKKoAP AdsZ6mXm3fcvlq+yb5YV0Dp59sIkR2uOhek3utFnW0mklrOFivL2rynCBC1W1la25tDxuMep9KScO uT91n0UrbILSFQGKPJBUjApwwssE88zy9eJwmrK+Q5J41tGw3kj7vugw1h34x0tqNXdTOJFm6XFm+ JsH51N4g==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.94 #2 (Red Hat Linux)) id 1lM6CU-001l0l-Q6; Tue, 16 Mar 2021 09:41:21 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 3A361304D58; Tue, 16 Mar 2021 10:41:14 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 175392D1CC08F; Tue, 16 Mar 2021 10:41:14 +0100 (CET) Date: Tue, 16 Mar 2021 10:41:14 +0100 From: Peter Zijlstra To: Huaixin Chang Cc: bsegall@google.com, dietmar.eggemann@arm.com, juri.lelli@redhat.com, khlebnikov@yandex-team.ru, linux-kernel@vger.kernel.org, mgorman@suse.de, mingo@redhat.com, odin@uged.al, odin@ugedal.com, pauld@redhead.com, pjt@google.com, rostedt@goodmis.org, shanpeic@linux.alibaba.com, tj@kernel.org, vincent.guittot@linaro.org, xiyou.wangcong@gmail.com Subject: Re: [PATCH v4 1/4] sched/fair: Introduce primitives for CFS bandwidth burst Message-ID: References: <20210316044931.39733-1-changhuaixin@linux.alibaba.com> <20210316044931.39733-2-changhuaixin@linux.alibaba.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210316044931.39733-2-changhuaixin@linux.alibaba.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Mar 16, 2021 at 12:49:28PM +0800, Huaixin Chang wrote: > In this patch, we introduce the notion of CFS bandwidth burst. Unused > "quota" from pervious "periods" might be accumulated and used in the > following "periods". The maximum amount of accumulated bandwidth is > bounded by "burst". And the maximun amount of CPU a group can consume in > a given period is "buffer" which is equivalent to "quota" + "burst in > case that this group has done enough accumulation. Complete lack of why though. Why am I going to spend time looking at this?