[PATCH 068/112] ACPI: Update the t-state for every affected cpu when t-state is changed

Len Brown
2008-02-07T09:36:27Z

From: Zhao Yakui <yakui.zhao@intel.com>

According to ACPI spec, the _TSD object provides T-state control cross
logical processor dependency information to OSPM. So the t-state
coordination should be considered when T-state for one cpu is changed.

According to ACPI spec, three types of coordination are defined.
SW_ALL, SW_ANY and HW_ALL.

SW_ALL: it means that OSPM needs to initiate T-state transition on
all processors in the domain. It is necessary to call throttling set function
for all affected cpus.

SW_ANY: it means that OSPM may initiate T-state transition on any processor in
the domain.

HW_ALL: Spec only says that hardware will perform the coordination and doesn't
recommend how OSPM coordinate T-state among the affected cpus. So it is treated
as the type of SW_ALL. It means that OSPM needs to initiate t-state transition
on all the processors in the domain.

Signed-off-by: Zhao Yakui <yakui.zhao@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>
---
drivers/acpi/processor_throttling.c | 79 ++++++++++++++++++++++++++++++++--
1 files changed, 74 insertions(+), 5 deletions(-)

diff --git a/drivers/acpi/processor_throttling.c b/drivers/acpi/processor_throttling.c
index 18a873a..86c790e 100644
--- a/drivers/acpi/processor_throttling.c
+++ b/drivers/acpi/processor_throttling.c
@@ -68,7 +68,7 @@ static int acpi_processor_update_tsd_coord(void)

/*
* Now that we have _TSD data from all CPUs, lets setup T-state
- * coordination among all CPUs.
+ * coordination between all CPUs.
*/
for_each_possible_cpu(i) {
pr = processors[i];
@@ -988,6 +988,11 @@ int acpi_processor_set_throttling(struct acpi_processor *pr, int state)
{
cpumask_t saved_mask;
int ret;
+ unsigned int i;
+ struct acpi_processor *match_pr;
+ struct acpi_processor_throttling *p_throttling;
+ struct throttling_tstate t_state;
+ cpumask_t online_throttling_cpus;

if (!pr)
return -EINVAL;
@@ -998,12 +1003,76 @@ int acpi_processor_set_throttling(struct acpi_processor *pr, int state)
if ((state < 0) || (state > (pr->throttling.state_count - 1)))
return -EINVAL;

+ saved_mask = current->cpus_allowed;
+ t_state.target_state = state;
+ p_throttling = &(pr->throttling);
+ cpus_and(online_throttling_cpus, cpu_online_map,
+ p_throttling->shared_cpu_map);
/*
- * Migrate task to the cpu pointed by pr.
+ * The throttling notifier will be called for every
+ * affected cpu in order to get one proper T-state.
+ * The notifier event is THROTTLING_PRECHANGE.
*/
- saved_mask = current->cpus_allowed;
- set_cpus_allowed(current, cpumask_of_cpu(pr->id));
- ret = pr->throttling.acpi_processor_set_throttling(pr, state);
+ for_each_cpu_mask(i, online_throttling_cpus) {
+ t_state.cpu = i;
+ acpi_processor_throttling_notifier(THROTTLING_PRECHANGE,
+ &t_state);
+ }
+ /*
+ * The function of acpi_processor_set_throttling will be called
+ * to switch T-state. If the coordination type is SW_ALL or HW_ALL,
+ * it is necessary to call it for every affected cpu. Otherwise
+ * it can be called only for the cpu pointed by pr.
+ */
+ if (p_throttling->shared_type == DOMAIN_COORD_TYPE_SW_ANY) {
+ set_cpus_allowed(current, cpumask_of_cpu(pr->id));
+ ret = p_throttling->acpi_processor_set_throttling(pr,
+ t_state.target_state);
+ } else {
+ /*
+ * When the T-state coordination is SW_ALL or HW_ALL,
+ * it is necessary to set T-state for every affected
+ * cpus.
+ */
+ for_each_cpu_mask(i, online_throttling_cpus) {
+ match_pr = processors[i];
+ /*
+ * If the pointer is invalid, we will report the
+ * error message and continue.
+ */
+ if (!match_pr) {
+ ACPI_DEBUG_PRINT((ACPI_DB_INFO,
+ "Invalid Pointer for CPU %d\n", i));
+ continue;
+ }
+ /*
+ * If the throttling control is unsupported on CPU i,
+ * we will report the error message and continue.
+ */
+ if (!match_pr->flags.throttling) {
+ ACPI_DEBUG_PRINT((ACPI_DB_INFO,
+ "Throttling Controll is unsupported "
+ "on CPU %d\n", i));
+ continue;
+ }
+ t_state.cpu = i;
+ set_cpus_allowed(current, cpumask_of_cpu(i));
+ ret = match_pr->throttling.
+ acpi_processor_set_throttling(
+ match_pr, t_state.target_state);
+ }
+ }
+ /*
+ * After the set_throttling is called, the
+ * throttling notifier is called for every
+ * affected cpu to update the T-states.
+ * The notifier event is THROTTLING_POSTCHANGE
+ */
+ for_each_cpu_mask(i, online_throttling_cpus) {
+ t_state.cpu = i;
+ acpi_processor_throttling_notifier(THROTTLING_POSTCHANGE,
+ &t_state);
+ }
/* restore the previous state */
set_cpus_allowed(current, saved_mask);
return ret;
--
1.5.4.23.gef5b9