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=-2.0 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_MUTT autolearn=ham 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 59125C43613 for ; Fri, 21 Jun 2019 12:37:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 28C8C208C3 for ; Fri, 21 Jun 2019 12:37:04 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="QqilS2cT" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726736AbfFUMhC (ORCPT ); Fri, 21 Jun 2019 08:37:02 -0400 Received: from merlin.infradead.org ([205.233.59.134]:53252 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726260AbfFUMhC (ORCPT ); Fri, 21 Jun 2019 08:37:02 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.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:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=7d0AOZocI1Q8mX1LNBJNSJm0RkC99Q9KWsCv6Fj3D2U=; b=QqilS2cTBLO5CxZgnbs9vg0AZ Fw+7J7SF13LrD1619BXFTIM5UIvwH4y6SUicD1rJb09/2Dl0DbdaWDiHspbwMtiJtDCRSoJt2Q3jU uqpkRNSpjtzBiPF0iDIoY99ViCz0W5OEmCrGolSJCE3SGXsSN9j+/Ja9zMkc0Mg84HZO1rZ3WL+zb t9jbe1HQRgc3aJSRZIaDsR86V8mPZ2ag7k87LFOLm62b6Kt+FJMyk8A0sWMKoSEkj4FY5Ybvj7K3b 5PUC8nOFttIt//Y1WnBxZudT1nUZWBnuwS8NiaBI9UHrNM5X8D7q+OkJcOczv6Ob7SzL4N6B04IcS phsCUloxA==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=hirez.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.92 #3 (Red Hat Linux)) id 1heImL-0000Te-BO; Fri, 21 Jun 2019 12:36:29 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 85A14203C6955; Fri, 21 Jun 2019 14:36:25 +0200 (CEST) Date: Fri, 21 Jun 2019 14:36:25 +0200 From: Peter Zijlstra To: xiaoggchen@tencent.com Cc: jasperwang@tencent.com, heddchen@tencent.com, mingo@redhat.com, linux-kernel@vger.kernel.org, tj@kernel.org, lizefan@huawei.com, hannes@cmpxchg.org, cgroups@vger.kernel.org Subject: Re: [PATCH 0/5] BT scheduling class Message-ID: <20190621123625.GJ3436@hirez.programming.kicks-ass.net> References: <1561103157-11246-1-git-send-email-xiaoggchen@tencent.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1561103157-11246-1-git-send-email-xiaoggchen@tencent.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jun 21, 2019 at 03:45:52PM +0800, xiaoggchen@tencent.com wrote: > From: chen xiaoguang > > This patch set introduces a new scheduler, we name it BT scheduler > for the moment. > The BT scheduler is similar with the CFS scheduler. We also use the > rb-tree as the run queue to save the runnable tasks. And the vruntime > concept is also used in the BT scheduler. And the priority of BT scheduler > is from 140 to 179. So now the schedulers in the kernel are as follows: > deadline, RT, CFS, BT and idle. NAK; it has no forward progress guarantees. This is also the reason why SCHED_IDLE is not a true idle time scheduler but a very low weight CFS tasks. It also has some very 'interesting' starvation cases, consider one of your BT tasks owns a mutex, but then there are there are runnable CFS tasks. The BT task will never get runtime and release the mutex. Also; NAK at all the duplication.