The patch titled
Subject: Migrate shutdown/reboot to boot cpu
has been added to the -mm tree. Its filename is
migrate-shutdown-reboot-to-boot-cpu.patch
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------------------------------------------------------
From: Robin Holt <holt@xxxxxxx>
Subject: 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 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>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/sys.c | 29 ++++++++++++++++++++++++++---
1 file changed, 26 insertions(+), 3 deletions(-)
diff -puN kernel/sys.c~migrate-shutdown-reboot-to-boot-cpu kernel/sys.c
--- a/kernel/sys.c~migrate-shutdown-reboot-to-boot-cpu
+++ a/kernel/sys.c
@@ -362,6 +362,29 @@ 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 reboot_cpu = 0;
+
+ cpu_hotplug_disable();
+
+ /* Make certain the cpu I'm about to reboot on is online */
+ if (!cpu_online(reboot_cpu))
+ reboot_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(reboot_cpu));
+}
+
/**
* kernel_restart - reboot the system
* @cmd: pointer to buffer containing command to execute for restart
@@ -373,7 +396,7 @@ 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");
@@ -400,7 +423,7 @@ 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);
@@ -419,7 +442,7 @@ 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 -mm which might be from holt@xxxxxxx are
origin.patch
mm-mmu_notifier-re-fix-freed-page-still-mapped-in-secondary-mmu.patch
mm-mmu_notifier-re-fix-freed-page-still-mapped-in-secondary-mmu-fix.patch
cpu-hotplug-provide-a-generic-helper-to-disable-enable-cpu-hotplug.patch
migrate-shutdown-reboot-to-boot-cpu.patch
remove-stable-friendly-pf_thread_bound-define.patch
move-shutdown-reboot-related-functions-to-kernel-rebootc.patch
checkpatchpl-the-new-kernel-rebootc-file.patch
x86-prepare-reboot_mode-for-moving-to-generic-kernel-code.patch
unicore32-prepare-reboot_mode-for-moving-to-generic-kernel-code.patch
arm-remove-unused-restart_mode-fields-from-some-arm-subarchs.patch
arm-prepare-reboot_mode-for-moving-to-generic-kernel-code.patch
arm-change-reboot_mode-to-use-enum-reboot_mode.patch
move-arch-x86-reboot=-handling-to-generic-kernel.patch
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