This is a note to let you know that I've just added the patch titled
reboot: rigrate shutdown/reboot to boot cpu
to the 3.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
reboot-rigrate-shutdown-reboot-to-boot-cpu.patch
and it can be found in the queue-3.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From cf7df378aa4ff7da3a44769b7ff6e9eef1a9f3db Mon Sep 17 00:00:00 2001
From: Robin Holt <holt@xxxxxxx>
Date: Wed, 12 Jun 2013 14:04:37 -0700
Subject: reboot: rigrate shutdown/reboot to boot cpu
From: Robin Holt <holt@xxxxxxx>
commit cf7df378aa4ff7da3a44769b7ff6e9eef1a9f3db upstream.
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
f96972f2dc63 ("kernel/sys.c: call disable_nonboot_cpus() in
kernel_restart()").
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 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 <holt@xxxxxxx>
Tested-by: Shawn Guo <shawn.guo@xxxxxxxxxx>
Cc: "Srivatsa S. Bhat" <srivatsa.bhat@xxxxxxxxxxxxxxxxxx>
Cc: H. Peter Anvin <hpa@xxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxx>
Cc: Russ Anderson <rja@xxxxxxx>
Cc: Robin Holt <holt@xxxxxxx>
Cc: Russell King <linux@xxxxxxxxxxxxxxxx>
Cc: Guan Xuetao <gxt@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
kernel/sys.c | 29 ++++++++++++++++++++++++++---
1 file changed, 26 insertions(+), 3 deletions(-)
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -353,6 +353,29 @@ int unregister_reboot_notifier(struct no
}
EXPORT_SYMBOL(unregister_reboot_notifier);
+/* Add backwards compatibility for stable trees. */
+#ifndef PF_NO_SETAFFINITY
+#define PF_NO_SETAFFINITY PF_THREAD_BOUND
+#endif
+
+static void migrate_to_reboot_cpu(void)
+{
+ /* The boot cpu is always logical cpu 0 */
+ int cpu = 0;
+
+ cpu_hotplug_disable();
+
+ /* Make certain the cpu I'm about to reboot on is online */
+ if (!cpu_online(cpu))
+ cpu = cpumask_first(cpu_online_mask);
+
+ /* Prevent races with other tasks migrating this task */
+ current->flags |= PF_NO_SETAFFINITY;
+
+ /* Make certain I only run on the appropriate processor */
+ set_cpus_allowed_ptr(current, cpumask_of(cpu));
+}
+
/**
* kernel_restart - reboot the system
* @cmd: pointer to buffer containing command to execute for restart
@@ -364,7 +387,7 @@ EXPORT_SYMBOL(unregister_reboot_notifier
void kernel_restart(char *cmd)
{
kernel_restart_prepare(cmd);
- disable_nonboot_cpus();
+ migrate_to_reboot_cpu();
syscore_shutdown();
if (!cmd)
printk(KERN_EMERG "Restarting system.\n");
@@ -391,7 +414,7 @@ static void kernel_shutdown_prepare(enum
void kernel_halt(void)
{
kernel_shutdown_prepare(SYSTEM_HALT);
- disable_nonboot_cpus();
+ migrate_to_reboot_cpu();
syscore_shutdown();
printk(KERN_EMERG "System halted.\n");
kmsg_dump(KMSG_DUMP_HALT);
@@ -410,7 +433,7 @@ void kernel_power_off(void)
kernel_shutdown_prepare(SYSTEM_POWER_OFF);
if (pm_power_off_prepare)
pm_power_off_prepare();
- disable_nonboot_cpus();
+ migrate_to_reboot_cpu();
syscore_shutdown();
printk(KERN_EMERG "Power down.\n");
kmsg_dump(KMSG_DUMP_POWEROFF);
Patches currently in stable-queue which might be from holt@xxxxxxx are
queue-3.4/cpu-hotplug-provide-a-generic-helper-to-disable-enable-cpu-hotplug.patch
queue-3.4/reboot-rigrate-shutdown-reboot-to-boot-cpu.patch
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