[PATCH 5/10] cpu bulk removal core changes
From: Shaohua Li
Date: Mon May 08 2006 - 01:48:50 EST
Core changes for cpu bulk removal. Modifies several functions to work with
cpumask_t.
Signed-off-by: Ashok Raj <ashok.raj@xxxxxxxxx>
Signed-off-by: Shaohua Li <shaohua.li@xxxxxxxxx>
---
linux-2.6.17-rc3-root/kernel/cpu.c | 125 ++++++++++++++++++++++++++++---------
1 files changed, 97 insertions(+), 28 deletions(-)
diff -puN kernel/cpu.c~cpu-bulk-remove-core kernel/cpu.c
--- linux-2.6.17-rc3/kernel/cpu.c~cpu-bulk-remove-core 2006-05-07 07:45:45.000000000 +0800
+++ linux-2.6.17-rc3-root/kernel/cpu.c 2006-05-07 07:45:45.000000000 +0800
@@ -82,29 +82,94 @@ void unregister_cpu_notifier(struct noti
EXPORT_SYMBOL(unregister_cpu_notifier);
#ifdef CONFIG_HOTPLUG_CPU
-static inline void check_for_tasks(int cpu)
+static inline void check_for_tasks(cpumask_t remove_mask)
{
struct task_struct *p;
write_lock_irq(&tasklist_lock);
for_each_process(p) {
- if (task_cpu(p) == cpu &&
+ if (cpu_isset(task_cpu(p), remove_mask) &&
(!cputime_eq(p->utime, cputime_zero) ||
!cputime_eq(p->stime, cputime_zero)))
printk(KERN_WARNING "Task %s (pid = %d) is on cpu %d\
(state = %ld, flags = %lx) \n",
- p->comm, p->pid, cpu, p->state, p->flags);
+ p->comm, p->pid, task_cpu(p), p->state, p->flags);
}
write_unlock_irq(&tasklist_lock);
}
+/* on success, the cpu will be cleared from mask */
+static int bulk_cpu_notify(cpumask_t *mask, unsigned long val)
+{
+ int cpu, err = NOTIFY_DONE;
+
+ for_each_cpu_mask(cpu, *mask) {
+ err = blocking_notifier_call_chain(&cpu_chain, val,
+ (void *)(long)cpu);
+ if (err == NOTIFY_BAD)
+ break;
+ cpu_clear(cpu, *mask);
+ }
+
+ return err;
+}
+
+static int prepare_bulk_cpu_remove(cpumask_t remove_mask)
+{
+ int err, err1 = NOTIFY_DONE;
+ cpumask_t orig_mask, recover_mask;
+ char str[NR_CPUS];
+
+ orig_mask = remove_mask;
+ err = bulk_cpu_notify(&remove_mask, CPU_DOWN_PREPARE);
+
+ if (err == NOTIFY_BAD) {
+ /*
+ * remove_mask now contains cpus not notified with DOWN_PREPARE
+ */
+ cpumask_scnprintf(str, NR_CPUS, remove_mask);
+ printk("%s: attempt to take down CPU: %s failed\n",
+ __FUNCTION__, str);
+
+ /*
+ * recover_mask = orig_mask & ~remove_mask
+ * this should yeild cpus already notified successfully
+ */
+ cpus_andnot(recover_mask, orig_mask, remove_mask);
+ if (!cpus_empty(recover_mask))
+ err1 = bulk_cpu_notify(&recover_mask, CPU_DOWN_FAILED);
+
+ if (err1 == NOTIFY_BAD)
+ BUG();
+ }
+ return err;
+}
+
+static void wait_to_leave_idle(cpumask_t mask)
+{
+ int cpu;
+
+ for_each_cpu_mask(cpu, mask) {
+ while (!idle_cpu(cpu))
+ yield();
+ }
+}
+
+static void bulk_migrate_tasks(cpumask_t mask)
+{
+ int cpu;
+ for_each_cpu_mask(cpu, mask)
+ migrate_tasks_off_dead_cpu(cpu);
+}
+
/* Take this CPU down. */
-static int take_cpu_down(void *unused)
+static int take_cpu_down(void *data)
{
int err;
+ cpumask_t remove_mask = *(cpumask_t *)data;
/* Ensure this CPU doesn't handle any more interrupts. */
- err = __cpu_disable(cpumask_of_cpu(raw_smp_processor_id()));
+ err = __cpu_disable(remove_mask);
if (err < 0)
return err;
@@ -114,7 +179,7 @@ static int take_cpu_down(void *unused)
return 0;
}
-int cpu_down(unsigned int cpu)
+int cpu_down_mask(cpumask_t remove_mask)
{
int err;
struct task_struct *p;
@@ -123,51 +188,50 @@ int cpu_down(unsigned int cpu)
if ((err = lock_cpu_hotplug_interruptible()) != 0)
return err;
- if (num_online_cpus() == 1) {
+ cpus_andnot(tmp, cpu_online_map, remove_mask);
+ if (cpus_empty(tmp)) {
err = -EBUSY;
goto out;
}
- if (!cpu_online(cpu)) {
+ cpus_and(tmp, cpu_online_map, remove_mask);
+ if (!cpus_equal(tmp, remove_mask)) {
err = -EINVAL;
goto out;
}
- err = blocking_notifier_call_chain(&cpu_chain, CPU_DOWN_PREPARE,
- (void *)(long)cpu);
+ err = prepare_bulk_cpu_remove(remove_mask);
if (err == NOTIFY_BAD) {
- printk("%s: attempt to take down CPU %u failed\n",
- __FUNCTION__, cpu);
err = -EINVAL;
goto out;
}
- /* Ensure that we are not runnable on dying cpu */
+ /* Ensure that we are not runnable on any dying cpu */
old_allowed = current->cpus_allowed;
- tmp = CPU_MASK_ALL;
- cpu_clear(cpu, tmp);
+ cpus_andnot(tmp, CPU_MASK_ALL, remove_mask);
set_cpus_allowed(current, tmp);
- p = __stop_machine_run(take_cpu_down, NULL, cpumask_of_cpu(cpu));
+ p = __stop_machine_run(take_cpu_down, &remove_mask, remove_mask);
if (IS_ERR(p)) {
/* CPU didn't die: tell everyone. Can't complain. */
- if (blocking_notifier_call_chain(&cpu_chain, CPU_DOWN_FAILED,
- (void *)(long)cpu) == NOTIFY_BAD)
+ tmp = remove_mask;
+ if (bulk_cpu_notify(&tmp, CPU_DOWN_FAILED) == NOTIFY_BAD)
BUG();
err = PTR_ERR(p);
goto out_allowed;
}
- if (cpu_online(cpu))
+ /* FIXME: recover some CPUs */
+ cpus_and(tmp, cpu_online_map, remove_mask);
+ if (!cpus_empty(tmp))
goto out_thread;
- /* Wait for it to sleep (leaving idle task). */
- while (!idle_cpu(cpu))
- yield();
+ /* Wait for them to sleep (leaving idle task). */
+ wait_to_leave_idle(remove_mask);
- /* This actually kills the CPU. */
- __cpu_die(cpumask_of_cpu(cpu));
+ /* This actually kills the CPUs. */
+ __cpu_die(remove_mask);
/* Move it here so it can run. */
kthread_bind(p, get_cpu());
@@ -178,12 +242,12 @@ int cpu_down(unsigned int cpu)
* we explictly call migrate_tasks here, otherwise there is a deadlock,
* one cpu's notifier handler is waiting for tasks in other dead CPUs
*/
- migrate_tasks_off_dead_cpu(cpu);
- if (blocking_notifier_call_chain(&cpu_chain, CPU_DEAD,
- (void *)(long)cpu) == NOTIFY_BAD)
+ bulk_migrate_tasks(remove_mask);
+ tmp = remove_mask;
+ if (bulk_cpu_notify(&tmp, CPU_DEAD) == NOTIFY_BAD)
BUG();
- check_for_tasks(cpu);
+ check_for_tasks(remove_mask);
out_thread:
err = kthread_stop(p);
@@ -193,6 +257,11 @@ out:
unlock_cpu_hotplug();
return err;
}
+
+int cpu_down(unsigned int cpu)
+{
+ return cpu_down_mask(cpumask_of_cpu(cpu));
+}
#endif /*CONFIG_HOTPLUG_CPU*/
int __devinit cpu_up(unsigned int cpu)
_
-
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