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=-2.3 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,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 D01FAC04E53 for ; Wed, 15 May 2019 16:37:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9619620873 for ; Wed, 15 May 2019 16:37:59 +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="bIpHC5/O" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726916AbfEOQh7 (ORCPT ); Wed, 15 May 2019 12:37:59 -0400 Received: from merlin.infradead.org ([205.233.59.134]:48744 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726520AbfEOQh6 (ORCPT ); Wed, 15 May 2019 12:37:58 -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=OtMvEXRStSFfAAGIbWQmGKZWz5rWXJEj2aQ6RYI6efI=; b=bIpHC5/OJWt+EW0yH5oJoix53 Yo6l9W5Z/jkqvOKRRVXc4gbZFnZ4MnECgs5PXJ/ieEumhruTuadQshGB6iGJtG8UuTLkOgVR/VJE9 a5BiM2mmPAC+SuQoK8A6ct7iakYS/2l9HOSE1aOxYv6p2JZ1EsRrJKEH9mQssVVZVGWTmnjgw6hps usaBuZE6qgazdHL6SAMJ9xznNW0gYBl2AwCrXUACQAlDiMrvvgfVdkWJ8Pi/9kxl3/gLtbn1LXBpN /i7OYeja6dF5WPZ7NiMGBozw9RDvzMz1joQqMcRpVD4DJVPLNIJRvDPbUTRiHJI0tGPL4xURxe+dK VYEmHiZkA==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=hirez.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1hQwuf-0001Fy-Dt; Wed, 15 May 2019 16:37:53 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 0D2042029906B; Wed, 15 May 2019 18:37:52 +0200 (CEST) Date: Wed, 15 May 2019 18:37:52 +0200 From: Peter Zijlstra To: Parth Shah Cc: linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, mingo@redhat.com, dietmar.eggemann@arm.com, dsmythies@telus.net Subject: Re: [RFCv2 4/6] sched/fair: Define core capacity to limit task packing Message-ID: <20190515163751.GW2589@hirez.programming.kicks-ass.net> References: <20190515135322.19393-1-parth@linux.ibm.com> <20190515135322.19393-5-parth@linux.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190515135322.19393-5-parth@linux.ibm.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 Wed, May 15, 2019 at 07:23:20PM +0530, Parth Shah wrote: > The task packing on a core needs to be bounded based on its capacity. This > patch defines a new method which acts as a tipping point for task packing. > > The Core capacity is the method which limits task packing above certain > point. In general, the capacity of a core is defined to be the aggregated > sum of all the CPUs in the Core. > > Some architectures does not have core capacity linearly increasing with the > number of threads( or CPUs) in the core. For such cases, architecture > specific calculations needs to be done to find core capacity. > > The `arch_scale_core_capacity` is currently tuned for `powerpc` arch by > scaling capacity w.r.t to the number of online SMT in the core. > > The patch provides default handler for other architecture by scaling core > capacity w.r.t. to the capacity of all the threads in the core. > > ToDo: SMT mode is calculated each time a jitter task wakes up leading to > redundant decision time which can be eliminated by keeping track of online > CPUs during hotplug task. Urgh, we just got rid of capacity for SMT. Also I don't think the above clearly defines your metric.