On Mon, Apr 15, 2013 at 12:16:44PM +0200, Ingo Molnar wrote: > > * Robin Holt <[email protected]> wrote: > > > From 1767003c943325e52ac78cac6fdbaf2ab638888d Mon Sep 17 00:00:00 2001 > > From: Robin Holt <[email protected]> > > 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 <[email protected]> > > To: Shawn Guo <[email protected]> > > To: Ingo Molnar <[email protected]> > > To: Russ Anderson <[email protected]> > > Cc: Andrew Morton <[email protected]> > > Cc: "H. Peter Anvin" <[email protected]> > > Cc: Lai Jiangshan <[email protected]> > > Cc: Linus Torvalds <[email protected]> > > Cc: Linux Kernel Mailing List <[email protected]> > > Cc: Michel Lespinasse <[email protected]> > > Cc: Oleg Nesterov <[email protected]> > > Cc: "Paul E. McKenney" <[email protected]> > > Cc: Paul Mackerras <[email protected]> > > Cc: Peter Zijlstra <[email protected]> > > Cc: Robin Holt <[email protected]> > > Cc: "[email protected]" <[email protected]> > > Cc: Tejun Heo <[email protected]> > > Cc: the arch/x86 maintainers <[email protected]> > > Cc: Thomas Gleixner <[email protected]> > > Cc: <[email protected]> > > --- > > 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 [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
