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Message-Id: <1285872613.2676.4.camel@sbsiddha-MOBL3.sc.intel.com>
Date: Thu, 30 Sep 2010 11:50:13 -0700
From: Suresh Siddha <suresh.b.siddha@...el.com>
To: Len Brown <lenb@...nel.org>, LKML <linux-kernel@...r.kernel.org>
Cc: Arjan van de Ven <arjan@...ux.intel.com>
Subject: [patch] intel_idle: Voluntary leave_mm before entering deeper
c-states
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 processor idle driver does this and was left out when intel idle
got introduced.
Signed-off-by: Suresh Siddha <suresh.b.siddha@...el.com>
---
diff --git a/drivers/idle/intel_idle.c b/drivers/idle/intel_idle.c
index a10152b..dff4663 100755
--- a/drivers/idle/intel_idle.c
+++ b/drivers/idle/intel_idle.c
@@ -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);
diff --git a/include/linux/cpuidle.h b/include/linux/cpuidle.h
index 36ca972..1be416b 100644
--- a/include/linux/cpuidle.h
+++ b/include/linux/cpuidle.h
@@ -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)
--
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