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intel_idle: Voluntary leave_mm before entering deeper 

Avoid TLB flush IPIs for the cores in deeper c-states by voluntary leave_mm()
before entering into that state. CPUs tend to flush TLB in those c-states
anyways.

acpi_idle does this with C3-type states, but it was not caried over
when intel_idle was introduced.  intel_idle can apply it
to C-states in addition to those that ACPI might export as C3...

Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>
This commit is contained in:
Suresh Siddha 2010-09-30 21:19:07 -04:00 committed by Len Brown
parent 9587a678fa
commit 6110a1f43c
2 changed files with 15 additions and 4 deletions
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18
drivers/idle/intel_idle.c
View File

@ -108,7 +108,7 @@ static struct cpuidle_state nehalem_cstates[MWAIT_MAX_NUM_CSTATES] = {
.name = "NHM-C3",
.desc = "MWAIT 0x10",
.driver_data = (void *) 0x10,
.flags = CPUIDLE_FLAG_TIME_VALID,
.flags = CPUIDLE_FLAG_TIME_VALID | CPUIDLE_FLAG_TLB_FLUSHED,
.exit_latency = 20,
.power_usage = 500,
.target_residency = 80,
@ -117,7 +117,7 @@ static struct cpuidle_state nehalem_cstates[MWAIT_MAX_NUM_CSTATES] = {
.name = "NHM-C6",
.desc = "MWAIT 0x20",
.driver_data = (void *) 0x20,
.flags = CPUIDLE_FLAG_TIME_VALID,
.flags = CPUIDLE_FLAG_TIME_VALID | CPUIDLE_FLAG_TLB_FLUSHED,
.exit_latency = 200,
.power_usage = 350,
.target_residency = 800,
@ -149,7 +149,7 @@ static struct cpuidle_state atom_cstates[MWAIT_MAX_NUM_CSTATES] = {
.name = "ATM-C4",
.desc = "MWAIT 0x30",
.driver_data = (void *) 0x30,
.flags = CPUIDLE_FLAG_TIME_VALID,
.flags = CPUIDLE_FLAG_TIME_VALID | CPUIDLE_FLAG_TLB_FLUSHED,
.exit_latency = 100,
.power_usage = 250,
.target_residency = 400,
@ -159,7 +159,7 @@ static struct cpuidle_state atom_cstates[MWAIT_MAX_NUM_CSTATES] = {
.name = "ATM-C6",
.desc = "MWAIT 0x40",
.driver_data = (void *) 0x40,
.flags = CPUIDLE_FLAG_TIME_VALID,
.flags = CPUIDLE_FLAG_TIME_VALID | CPUIDLE_FLAG_TLB_FLUSHED,
.exit_latency = 200,
.power_usage = 150,
.target_residency = 800,
@ -185,6 +185,16 @@ static int intel_idle(struct cpuidle_device *dev, struct cpuidle_state *state)
local_irq_disable();
/*
* If the state flag indicates that the TLB will be flushed or if this
* is the deepest c-state supported, do a voluntary leave mm to avoid
* costly and mostly unnecessary wakeups for flushing the user TLB's
* associated with the active mm.
*/
if (state->flags & CPUIDLE_FLAG_TLB_FLUSHED ||
(&dev->states[dev->state_count - 1] == state))
leave_mm(cpu);
if (!(lapic_timer_reliable_states & (1 << (cstate))))
clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ENTER, &cpu);

1
include/linux/cpuidle.h
View File

@ -53,6 +53,7 @@ struct cpuidle_state {
#define CPUIDLE_FLAG_BALANCED (0x40) /* medium latency, moderate savings */
#define CPUIDLE_FLAG_DEEP (0x80) /* high latency, large savings */
#define CPUIDLE_FLAG_IGNORE (0x100) /* ignore during this idle period */
#define CPUIDLE_FLAG_TLB_FLUSHED (0x200) /* tlb will be flushed */
#define CPUIDLE_DRIVER_FLAGS_MASK (0xFFFF0000)