Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753377Ab3DOP7X (ORCPT ); Mon, 15 Apr 2013 11:59:23 -0400 Received: from relay1.sgi.com ([192.48.179.29]:52327 "EHLO relay.sgi.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751854Ab3DOP7W (ORCPT ); Mon, 15 Apr 2013 11:59:22 -0400 Date: Mon, 15 Apr 2013 10:59:19 -0500 From: Robin Holt To: Ingo Molnar Cc: Robin Holt , "Srivatsa S. Bhat" , Paul Mackerras , Linus Torvalds , "H. Peter Anvin" , Andrew Morton , Linux Kernel Mailing List , Russ Anderson , Shawn Guo , Thomas Gleixner , Ingo Molnar , the arch/x86 maintainers , "Paul E. McKenney" , Tejun Heo , Oleg Nesterov , Lai Jiangshan , Michel Lespinasse , "rusty@rustcorp.com.au" , Peter Zijlstra Subject: Re: Bulk CPU Hotplug (Was Re: [PATCH] Do not force shutdown/reboot to boot cpu.) Message-ID: <20130415155919.GZ3658@sgi.com> References: <20130410111620.GB29752@gmail.com> <20130411053106.GA9042@drongo> <5166B05E.8010904@linux.vnet.ibm.com> <20130411134837.GE3672@sgi.com> <20130412053718.GC3887@gmail.com> <5167A52F.6020503@linux.vnet.ibm.com> <20130412093149.GT3658@sgi.com> <20130415101644.GC18024@gmail.com> <20130415120216.GX3658@sgi.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20130415120216.GX3658@sgi.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: 4420 Lines: 102 I have the patches sort-of finished. The patch set starts by moving the halt/shutdown/reboot functions over to a new kernel/reboot.c, next patch gets a checkpatch.pl cleanup to work, third patch is essentially the below patch against the new file, and the fourth patch introduces a kernel boot parameter. That said, I don't like them because of the 'stable' marking for these patches. I think I am going submit them with the existing patch first in the series, then introduce the kernel parameter, then move them to kernel/reboot.c, and finally pass checkpatch.pl. Does that sound alright? Robin On Mon, Apr 15, 2013 at 07:02:16AM -0500, Robin Holt wrote: > On Mon, Apr 15, 2013 at 12:16:44PM +0200, Ingo Molnar wrote: > > > > * Robin Holt wrote: > > > > > From 1767003c943325e52ac78cac6fdbaf2ab638888d Mon Sep 17 00:00:00 2001 > > > From: Robin Holt > > > Date: Wed, 3 Apr 2013 13:52:00 -0500 > > > Subject: [PATCH] Migrate shutdown/reboot to boot cpu. > > > > > > We recently noticed that reboot of a 1024 cpu machine takes approx 16 > > > minutes of just stopping the cpus. The slowdown was tracked to commit > > > f96972f. > > > > > > The current implementation does all the work of hot removing the cpus > > > before halting the system. We are switching to just migrating to the > > > boot cpu and then calling continuing with shutdown/reboot. > > > > > > This also has the effect of not breaking x86's command line parameter for > > > specifying the reboot cpu. Note, this code was shamelessly copied from > > > arch/x86/kernel/reboot.c with bits removed pertaining to the reboot_cpu > > > command line parameter. > > > > > > Signed-off-by: Robin Holt > > > To: Shawn Guo > > > To: Ingo Molnar > > > To: Russ Anderson > > > Cc: Andrew Morton > > > Cc: "H. Peter Anvin" > > > Cc: Lai Jiangshan > > > Cc: Linus Torvalds > > > Cc: Linux Kernel Mailing List > > > Cc: Michel Lespinasse > > > Cc: Oleg Nesterov > > > Cc: "Paul E. McKenney" > > > Cc: Paul Mackerras > > > Cc: Peter Zijlstra > > > Cc: Robin Holt > > > Cc: "rusty@rustcorp.com.au" > > > Cc: Tejun Heo > > > Cc: the arch/x86 maintainers > > > Cc: Thomas Gleixner > > > Cc: > > > --- > > > kernel/sys.c | 17 +++++++++++++++-- > > > 1 file changed, 15 insertions(+), 2 deletions(-) > > > > > > diff --git a/kernel/sys.c b/kernel/sys.c > > > index 0da73cf..4d1047d 100644 > > > --- a/kernel/sys.c > > > +++ b/kernel/sys.c > > > @@ -357,6 +357,19 @@ int unregister_reboot_notifier(struct notifier_block *nb) > > > } > > > EXPORT_SYMBOL(unregister_reboot_notifier); > > > > > > +void migrate_to_boot_cpu(void) > > > +{ > > > + /* The boot cpu is always logical cpu 0 */ > > > + int reboot_cpu_id = 0; > > > + > > > + /* Make certain the cpu I'm about to reboot on is online */ > > > + if (!cpu_online(reboot_cpu_id)) > > > + reboot_cpu_id = smp_processor_id(); > > > + > > > + /* Make certain I only run on the appropriate processor */ > > > + set_cpus_allowed_ptr(current, cpumask_of(reboot_cpu_id)); > > > +} > > > > I guess you suspect what I'm going to suggest next? :-) > > > > While I think something like this commit would be acceptable as a minimal > > regression fix, it would be really lovely to add a second patch as well, which > > removes the same code from arch/x86/kernel/reboot.c:native_machine_shutdown() and > > merged it with the kernel/sys.c version? That way all platforms gained a > > reboot_cpu command line, and we'd have less code duplication as well. Win-win. > > > > ( While at it, it might make sense to move the reboot/shutdown related bits from > > kernel/sys.c to a new kernel/shutdown.c or kernel/reboot.c file or so. ) > > That all sounds good. I will work on that this morning. > > Robin -- 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/