From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756477Ab2DTXMA (ORCPT ); Fri, 20 Apr 2012 19:12:00 -0400 Received: from mail-iy0-f174.google.com ([209.85.210.174]:64363 "EHLO mail-iy0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752370Ab2DTXL5 convert rfc822-to-8bit (ORCPT ); Fri, 20 Apr 2012 19:11:57 -0400 MIME-Version: 1.0 In-Reply-To: <20120420122120.097464672@linutronix.de> References: <20120420122120.097464672@linutronix.de> Date: Fri, 20 Apr 2012 16:11:56 -0700 Message-ID: Subject: Re: [patch 00/18] SMP: Boot and CPU hotplug refactoring - Part 1 From: Venki Pallipadi To: Thomas Gleixner Cc: LKML , linux-arch@vger.kernel.org, Peter Zijlstra , Rusty Russell , "Paul E. McKenney" , Ingo Molnar , "Srivatsa S. Bhat" Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8BIT X-System-Of-Record: true Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Apr 20, 2012 at 6:05 AM, Thomas Gleixner wrote: > Dear all, > > I'm working on refactoring the SMP boot and CPU hotplug implementation. > > The current code has evolved over time into a conglomerate of > warts. My main goals are to: > >  - reduce the architecture code by moving repeating constructs to the >   core > >  - redesigning the handling of per cpu threads. There is no point to >   tear down the threads just to create them again. > >  - restructuring the notifier facility into a proper tree with >   dependencies to avoid the gazillion of callbacks and moving >   setup/teardown code into the context of the upcoming/dying cpu > > The motivation behind this work is the cpu hotplug nightmare which we > are facing in the RT kernel and the requests from several groups > (e.g. ARM) to make hotplug more lightweight and faster. > > This first part moves the idle thread management for non-boot cpus > into the core. fork_idle() is called in a workqueue as it is > implemented in a few architectures already. This is necessary when not > all cpus are brought up by the early boot code as otherwise we would > take a ref on the user task VM of the thread which brings the cpu up > via the sysfs interface. > I had sent out a patchset that did this cleanup here: https://lkml.org/lkml/2012/3/6/466 This patchset is clean and more exhaustive than what I had. So, Acked-by: Venkatesh Pallipadi > This converts all architectures except m32r, mn10300, tile and UM to > the new core facility. These architecture are calling fork_idle() in > the very early boot code in smp_prepare_cpus() for unknown reasons. > I haven't analyzed yet, whether this is on purpose or can be moved > over to the generic facility. It'd be nice if the responsible maintainers > could look into that as well. > > Thanks, > >        tglx > > > > -- > 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/