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authorTejun Heo <tj@kernel.org>2010-05-06 18:49:20 +0200
committerTejun Heo <tj@kernel.org>2010-05-06 18:49:20 +0200
commit3fc1f1e27a5b807791d72e5d992aa33b668a6626 (patch)
tree396c2f49909c506c3ad53fd6a9bdddf6c24f7860 /kernel/cpu.c
parent1142d810298e694754498dbb4983fcb6cb7fd884 (diff)
downloadlinux-2.6.34-ux500-3fc1f1e27a5b807791d72e5d992aa33b668a6626.tar.gz
stop_machine: reimplement using cpu_stop
Reimplement stop_machine using cpu_stop. As cpu stoppers are guaranteed to be available for all online cpus, stop_machine_create/destroy() are no longer necessary and removed. With resource management and synchronization handled by cpu_stop, the new implementation is much simpler. Asking the cpu_stop to execute the stop_cpu() state machine on all online cpus with cpu hotplug disabled is enough. stop_machine itself doesn't need to manage any global resources anymore, so all per-instance information is rolled into struct stop_machine_data and the mutex and all static data variables are removed. The previous implementation created and destroyed RT workqueues as necessary which made stop_machine() calls highly expensive on very large machines. According to Dimitri Sivanich, preventing the dynamic creation/destruction makes booting faster more than twice on very large machines. cpu_stop resources are preallocated for all online cpus and should have the same effect. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Rusty Russell <rusty@rustcorp.com.au> Acked-by: Peter Zijlstra <peterz@infradead.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Dimitri Sivanich <sivanich@sgi.com>
Diffstat (limited to 'kernel/cpu.c')
-rw-r--r--kernel/cpu.c8
1 files changed, 0 insertions, 8 deletions
diff --git a/kernel/cpu.c b/kernel/cpu.c
index 914aedcde84..54577757477 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -266,9 +266,6 @@ int __ref cpu_down(unsigned int cpu)
{
int err;
- err = stop_machine_create();
- if (err)
- return err;
cpu_maps_update_begin();
if (cpu_hotplug_disabled) {
@@ -280,7 +277,6 @@ int __ref cpu_down(unsigned int cpu)
out:
cpu_maps_update_done();
- stop_machine_destroy();
return err;
}
EXPORT_SYMBOL(cpu_down);
@@ -361,9 +357,6 @@ int disable_nonboot_cpus(void)
{
int cpu, first_cpu, error;
- error = stop_machine_create();
- if (error)
- return error;
cpu_maps_update_begin();
first_cpu = cpumask_first(cpu_online_mask);
/*
@@ -394,7 +387,6 @@ int disable_nonboot_cpus(void)
printk(KERN_ERR "Non-boot CPUs are not disabled\n");
}
cpu_maps_update_done();
- stop_machine_destroy();
return error;
}