Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755307Ab1CXQwM (ORCPT ); Thu, 24 Mar 2011 12:52:12 -0400 Received: from e28smtp07.in.ibm.com ([122.248.162.7]:49314 "EHLO e28smtp07.in.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755108Ab1CXQwJ (ORCPT ); Thu, 24 Mar 2011 12:52:09 -0400 Date: Thu, 24 Mar 2011 22:22:00 +0530 From: Vaidyanathan Srinivasan To: Trinabh Gupta Cc: Len Brown , arjan@linux.intel.com, peterz@infradead.org, suresh.b.siddha@intel.com, benh@kernel.crashing.org, venki@google.com, ak@linux.intel.com, linux-kernel@vger.kernel.org, sfr@canb.auug.org.au, xen-devel@lists.xensource.com Subject: Re: [RFC PATCH V4 2/5] cpuidle: list based cpuidle driver registration and selection Message-ID: <20110324165200.GC16408@dirshya.in.ibm.com> Reply-To: svaidy@linux.vnet.ibm.com References: <20110322123208.28725.30945.stgit@tringupt.in.ibm.com> <20110322123233.28725.92874.stgit@tringupt.in.ibm.com> <4D89BBDD.5090505@linux.vnet.ibm.com> <4D8B5197.2060306@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline In-Reply-To: <4D8B5197.2060306@linux.vnet.ibm.com> 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: 1891 Lines: 48 * Trinabh Gupta [2011-03-24 19:43:43]: [snip] > >>But we also have to replace the functionality provided by pm_idle, > >>i.e. call default_idle for platforms where no better idle routine > >>exists, call mwait for pre-nehalem platforms, use intel_idle or > >>acpi_idle for nehalem architectures etc. To manage all this > >>we need a registration mechanism which is conveniently provided > >>by cpuidle. > > > >It isn't immediately clear to me that all of these options > >need to be preserved. > > So what do you suggest can be removed? Can we use safe_halt() until intel_idle/acpi_idle take over? But what if they do not take over? If safe_halt() is not very bad compared to the variants like mwait_idle and c1e_idle, then we can remove the old code and no need to move them to default driver. > >Are we suggesting that x86 must always build with cpuidle? > >I'm sure that somebody someplace will object to that. > > Arjan argued that since almost everyone today runs cpuidle > it may be best to include it in the kernel > (https://lkml.org/lkml/2010/10/20/243). But yes, we agreed > that we would have to make cpuidle lighter incrementally. > Making ladder governor optional could be one way for example. > > > >OTOH, if cpuidle is included, I'd like to see the > >non-cpuidle code excluded, since nobody will run it... The non-cpuidle code will be the select_idle_routine() and related function that cam move to default_driver that register to cpuidle. We can load on-demand as module if better routines fail to register. Maybe we don't need this at all as discussed in the above point? --Vaidy [snip] -- 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/