Messages in this thread Patch in this message | | | Date | Mon, 24 Jan 2011 02:34:18 -0500 | Subject | [PATCH] a patch to fix the cpu-offline-online problem caused by pm_idle | From | Luming Yu <> |
| |
Hi there,
I've seen many problems caused by deep-c-state-capable pm_idle on a NHM-EX system with this test script # for i in `seq 1 1000`; do echo $i; echo 0 > /sys/devices/system/cpu/cpu59/online ; sleep 1; echo 1 > /sys/devices/system/cpu/cpu59/online; done
As the bug " CPU online/offline causes system slowdown" https://bugzilla.redhat.com/show_bug.cgi?id=586551 described.
The simplest and easiest and cleanest way I can think of now is as the patch attached.
Signed-off-by: Yu Luming <luming.yu@intel.com>
diff --git a/kernel/cpu.c b/kernel/cpu.c index c75fcdd..d419eb3 100644 --- a/kernel/cpu.c +++ b/kernel/cpu.c @@ -135,6 +135,7 @@ int __ref register_cpu_notifier(struct notifier_block *nb)
#ifdef CONFIG_HOTPLUG_CPU
+static void (*pm_idle_saved) (void) __read_mostly; EXPORT_SYMBOL(register_cpu_notifier);
void __ref unregister_cpu_notifier(struct notifier_block *nb) @@ -145,6 +146,19 @@ void __ref unregister_cpu_notifier(struct notifier_block *nb) } EXPORT_SYMBOL(unregister_cpu_notifier);
+static inline void save_pm_idle(void) +{ + pm_idle_saved = pm_idle; + pm_idle = default_idle; + cpu_idle_wait(); +} + +static inline void restore_pm_idle(void) +{ + pm_idle = pm_idle_saved; + cpu_idle_wait(); +} + static inline void check_for_tasks(int cpu) { struct task_struct *p; @@ -278,7 +292,9 @@ int __ref cpu_down(unsigned int cpu) goto out; }
+ save_pm_idle(); err = _cpu_down(cpu, 0); + restore_pm_idle();
out: cpu_maps_update_done(); @@ -376,7 +392,9 @@ int __cpuinit cpu_up(unsigned int cpu) goto out; }
+ save_pm_idle(); err = _cpu_up(cpu, 0); + restore_pm_idle();
out: cpu_maps_update_done();[unhandled content-type:application/octet-stream] | |