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authorVenki Pallipadi <venkatesh.pallipadi@intel.com>2008-01-30 07:32:01 -0500
committerIngo Molnar <mingo@elte.hu>2008-01-30 07:32:01 -0500
commitbde6f5f59c2b2b48a7a849c129d5b48838fe77ee (patch)
tree4fa3befdfa227db56770a0dc85b8fc18be232f70 /drivers/acpi
parent7d409d6057c7244f8757ce15245f6df27271be0c (diff)
x86: voluntary leave_mm before entering ACPI C3
Aviod TLB flush IPIs during C3 states by voluntary leave_mm() before entering C3. The performance impact of TLB flush on C3 should not be significant with respect to C3 wakeup latency. Also, CPUs tend to flush TLB in hardware while in C3 anyways. On a 8 logical CPU system, running make -j2, the number of tlbflush IPIs goes down from 40 per second to ~ 0. Total number of interrupts during the run of this workload was ~1200 per second, which makes it ~3% savings in wakeups. There was no measurable performance or power impact however. [ akpm@linux-foundation.org: symbol export fixes. ] Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'drivers/acpi')
-rw-r--r--drivers/acpi/processor_idle.c2
1 files changed, 2 insertions, 0 deletions
diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c
index 2235f4e02d26..0721a8183c89 100644
--- a/drivers/acpi/processor_idle.c
+++ b/drivers/acpi/processor_idle.c
@@ -534,6 +534,7 @@ static void acpi_processor_idle(void)
534 break; 534 break;
535 535
536 case ACPI_STATE_C3: 536 case ACPI_STATE_C3:
537 acpi_unlazy_tlb(smp_processor_id());
537 /* 538 /*
538 * Must be done before busmaster disable as we might 539 * Must be done before busmaster disable as we might
539 * need to access HPET ! 540 * need to access HPET !
@@ -1423,6 +1424,7 @@ static int acpi_idle_enter_simple(struct cpuidle_device *dev,
1423 return 0; 1424 return 0;
1424 } 1425 }
1425 1426
1427 acpi_unlazy_tlb(smp_processor_id());
1426 /* 1428 /*
1427 * Must be done before busmaster disable as we might need to 1429 * Must be done before busmaster disable as we might need to
1428 * access HPET ! 1430 * access HPET !