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| author | Tejun Heo <tj@kernel.org> | 2010-05-06 18:49:20 +0200 |
|---|---|---|
| committer | Tejun Heo <tj@kernel.org> | 2010-05-06 18:49:20 +0200 |
| commit | 3fc1f1e27a5b807791d72e5d992aa33b668a6626 (patch) | |
| tree | 396c2f49909c506c3ad53fd6a9bdddf6c24f7860 /kernel/cpu.c | |
| parent | 1142d810298e694754498dbb4983fcb6cb7fd884 (diff) | |
| download | linux-3fc1f1e27a5b807791d72e5d992aa33b668a6626.tar.bz2 | |
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.c | 8 |
1 files changed, 0 insertions, 8 deletions
diff --git a/kernel/cpu.c b/kernel/cpu.c index 914aedcde849..545777574779 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; } |