Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753982Ab3C0Rlv (ORCPT ); Wed, 27 Mar 2013 13:41:51 -0400 Received: from fw-tnat.cambridge.arm.com ([217.140.96.21]:57126 "EHLO cam-smtp0.cambridge.arm.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752626Ab3C0Rls (ORCPT ); Wed, 27 Mar 2013 13:41:48 -0400 Date: Wed, 27 Mar 2013 17:37:42 +0000 From: Catalin Marinas To: Nicolas Pitre Cc: Peter Zijlstra , "tony.luck@intel.com" , "len.brown@intel.com" , "alex.shi@intel.com" , "linux@arm.linux.org.uk" , "corbet@lwn.net" , Arjan van de Ven , "mingo@kernel.org" , "linux-kernel@vger.kernel.org" , "cmetcalf@tilera.com" , "chander.kashyap@linaro.org" , "linaro-kernel@lists.linaro.org" , "preeti@linux.vnet.ibm.com" , "paulmck@linux.vnet.ibm.com" , "pjt@google.com" , Morten Rasmussen , "linux-arm-kernel@lists.infradead.org" Subject: Re: [RFC PATCH v3 3/6] sched: pack small tasks Message-ID: <20130327173742.GA17642@arm.com> References: <1363955155-18382-4-git-send-email-vincent.guittot@linaro.org> <1364301998.5053.17.camel@laptop> <5151BEF2.9090100@linux.intel.com> <1364373980.5053.57.camel@laptop> <1364374820.5053.63.camel@laptop> <20130327111855.GI801@MacBook-Pro.local> <1364393634.5053.71.camel@laptop> <20130327163642.GA1136@localhost.cambridge.arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1214 Lines: 27 On Wed, Mar 27, 2013 at 05:18:53PM +0000, Nicolas Pitre wrote: > On Wed, 27 Mar 2013, Catalin Marinas wrote: > > > So if the above works, the scheduler guys can mandate that little CPUs > > are always first and for ARM it would be a matter of getting the right > > CPU topology in the DT (independent of what hw vendors think of CPU > > topology) and booting Linux on CPU 4 etc. > > Just a note about that: if the scheduler mandates little CPUs first, > that should _not_ have any implications on the DT content. DT is not > about encoding Linux specific implementation details. It is simple > enough to tweak the CPU logical map at run time when enumeratiing CPUs. You are right, though a simpler way (hack) to tweak the cpu_logical_map is to change the DT ;). But the problem is that the kernel doesn't know which CPU is big and which is little, unless you specify this in some way via the DT. It can be the cpu nodes order or some other means. -- Catalin -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/