@@ -170,18 +170,37 @@ static struct cpuidle_state shared_states[MAX_IDLE_STATE_COUNT] = {
void update_smt_snooze_delay(int cpu, int residency)
{
struct cpuidle_driver *drv = cpuidle_get_driver();
- struct cpuidle_device *dev = per_cpu(cpuidle_devices, cpu);
+ struct cpuidle_device *dev;
if (cpuidle_state_table != dedicated_states)
return;
- if (residency < 0) {
- /* Disable the Nap state on that cpu */
- if (dev)
- dev->states_usage[1].disable = 1;
- } else
- if (drv)
+ if (!drv)
+ return;
+
+ if (cpu == -1) {
+ if (residency < 0) {
+ /* Disable NAP on all cpus */
+ drv->states[1].disabled = true;
+ return;
+ } else {
drv->states[1].target_residency = residency;
+ drv->states[1].disabled = false;
+ return;
+ }
+ }
+
+ dev = per_cpu(cpuidle_devices, cpu);
+ if (!dev)
+ return;
+
+ if (residency < 0)
+ dev->states_usage[1].disable = 1;
+ else {
+ drv->states[1].target_residency = residency;
+ drv->states[1].disabled = false;
+ dev->states_usage[1].disable = 0;
+ }
}
static int pseries_cpuidle_add_cpu_notifier(struct notifier_block *n,
@@ -331,6 +350,8 @@ static int __init pseries_processor_idle_init(void)
return retval;
}
+ update_smt_snooze_delay(-1, per_cpu(smt_snooze_delay, 0));
+
retval = pseries_idle_devices_init();
if (retval) {
pseries_idle_devices_uninit();
smt-snooze-delay is tunable provided currently on powerpc to delay the entry of an idle cpu to NAP state. By default, the value is 100us, which is entry criteria for NAP state i.e only if the idle period is above 100us it would enter NAP. Value of -1 disables entry into NAP. This value can be set either through sysfs, ppc64_cpu util or by passing it via kernel command line. Currently this feature is broken when the value is passed via the kernel command line. This patch aims to fix this, by taking the appropritate action based on the value after the pseries driver is registered. This check is carried on in the backend driver rather in setup_smt_snooze_delay() as one is not sure if the cpuidle driver is even registered when setup routine is executed. Also, this fixes re-enabling of NAP states by setting appropriate value without having to reboot. Also, to note is, smt-snooze-delay is per-cpu variable. This can be used to enable/disable NAP on per-cpu basis using sysfs but when this variable is passed via kernel command line or using the smt-snooze-delay it applies to all the cpus. Per-cpu tuning can only be done via sysfs. Signed-off-by: Deepthi Dharwar <deepthi@linux.vnet.ibm.com> --- arch/powerpc/platforms/pseries/processor_idle.c | 35 ++++++++++++++++++----- 1 file changed, 28 insertions(+), 7 deletions(-)