+++ /dev/null
-From stable-bounces@linux.kernel.org Tue Apr 7 03:18:08 2009
-Date: Mon, 06 Apr 2009 23:16:54 -0400 (EDT)
-From: Len Brown <lenb@kernel.org>
-To: stable@kernel.org
-Message-id: <alpine.LFD.2.00.0904062315480.5698@localhost.localdomain>
-Cc: linux-acpi@vger.kernel.org
-Subject: acpi: fix of pmtimer overflow that make Cx states time incorrect
-
-From: alex.shi <alex.shi@intel.com>
-
-upstream commit: ff69f2bba67bd45514923aaedbf40fe351787c59
-
-We found Cx states time abnormal in our some of machines which have 16
-LCPUs, the C0 take too many time while system is really idle when kernel
-enabled tickless and highres. powertop output is below:
-
- PowerTOP version 1.9 (C) 2007 Intel Corporation
-
-Cn Avg residency P-states (frequencies)
-C0 (cpu running) (40.5%) 2.53 Ghz 0.0%
-C1 0.0ms ( 0.0%) 2.53 Ghz 0.0%
-C2 128.8ms (59.5%) 2.40 Ghz 0.0%
- 1.60 Ghz 100.0%
-
-Wakeups-from-idle per second : 4.7 interval: 20.0s
-no ACPI power usage estimate available
-
-Top causes for wakeups:
- 41.4% ( 24.9) <interrupt> : extra timer interrupt
- 20.2% ( 12.2) <kernel core> : usb_hcd_poll_rh_status
-(rh_timer_func)
-
-After tacking detailed for this issue, Yakui and I find it is due to 24
-bit PM timer overflows when some of cpu sleep more than 4 seconds. With
-tickless kernel, the CPU want to sleep as much as possible when system
-idle. But the Cx sleep time are recorded by pmtimer which length is
-determined by BIOS. The current Cx time was gotten in the following
-function from driver/acpi/processor_idle.c:
-
-static inline u32 ticks_elapsed(u32 t1, u32 t2)
-{
- if (t2 >= t1)
- return (t2 - t1);
- else if (!(acpi_gbl_FADT.flags & ACPI_FADT_32BIT_TIMER))
- return (((0x00FFFFFF - t1) + t2) & 0x00FFFFFF);
- else
- return ((0xFFFFFFFF - t1) + t2);
-}
-
-If pmtimer is 24 bits and it take 5 seconds from t1 to t2, in above
-function, just about 1 seconds ticks was recorded. So the Cx time will be
-reduced about 4 seconds. and this is why we see above powertop output.
-
-To resolve this problem, Yakui and I use ktime_get() to record the Cx
-states time instead of PM timer as the following patch. the patch was
-tested with i386/x86_64 modes on several platforms.
-
-Acked-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
-Tested-by: Alex Shi <alex.shi@intel.com>
-Signed-off-by: Alex Shi <alex.shi@intel.com>
-Signed-off-by: Yakui.zhao <yakui.zhao@intel.com>
-Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
-Signed-off-by: Len Brown <len.brown@intel.com>
-Signed-off-by: Chris Wright <chrisw@sous-sol.org>
----
- drivers/acpi/processor_idle.c | 63 ++++++++++++++++++------------------------
- 1 file changed, 27 insertions(+), 36 deletions(-)
-
---- a/drivers/acpi/processor_idle.c
-+++ b/drivers/acpi/processor_idle.c
-@@ -64,7 +64,6 @@
- #define _COMPONENT ACPI_PROCESSOR_COMPONENT
- ACPI_MODULE_NAME("processor_idle");
- #define ACPI_PROCESSOR_FILE_POWER "power"
--#define US_TO_PM_TIMER_TICKS(t) ((t * (PM_TIMER_FREQUENCY/1000)) / 1000)
- #define PM_TIMER_TICK_NS (1000000000ULL/PM_TIMER_FREQUENCY)
- #define C2_OVERHEAD 1 /* 1us */
- #define C3_OVERHEAD 1 /* 1us */
-@@ -78,6 +77,10 @@ module_param(nocst, uint, 0000);
- static unsigned int latency_factor __read_mostly = 2;
- module_param(latency_factor, uint, 0644);
-
-+static s64 us_to_pm_timer_ticks(s64 t)
-+{
-+ return div64_u64(t * PM_TIMER_FREQUENCY, 1000000);
-+}
- /*
- * IBM ThinkPad R40e crashes mysteriously when going into C2 or C3.
- * For now disable this. Probably a bug somewhere else.
-@@ -159,25 +162,6 @@ static struct dmi_system_id __cpuinitdat
- {},
- };
-
--static inline u32 ticks_elapsed(u32 t1, u32 t2)
--{
-- if (t2 >= t1)
-- return (t2 - t1);
-- else if (!(acpi_gbl_FADT.flags & ACPI_FADT_32BIT_TIMER))
-- return (((0x00FFFFFF - t1) + t2) & 0x00FFFFFF);
-- else
-- return ((0xFFFFFFFF - t1) + t2);
--}
--
--static inline u32 ticks_elapsed_in_us(u32 t1, u32 t2)
--{
-- if (t2 >= t1)
-- return PM_TIMER_TICKS_TO_US(t2 - t1);
-- else if (!(acpi_gbl_FADT.flags & ACPI_FADT_32BIT_TIMER))
-- return PM_TIMER_TICKS_TO_US(((0x00FFFFFF - t1) + t2) & 0x00FFFFFF);
-- else
-- return PM_TIMER_TICKS_TO_US((0xFFFFFFFF - t1) + t2);
--}
-
- /*
- * Callers should disable interrupts before the call and enable
-@@ -853,7 +837,8 @@ static inline void acpi_idle_do_entry(st
- static int acpi_idle_enter_c1(struct cpuidle_device *dev,
- struct cpuidle_state *state)
- {
-- u32 t1, t2;
-+ ktime_t kt1, kt2;
-+ s64 idle_time;
- struct acpi_processor *pr;
- struct acpi_processor_cx *cx = cpuidle_get_statedata(state);
-
-@@ -871,14 +856,15 @@ static int acpi_idle_enter_c1(struct cpu
- return 0;
- }
-
-- t1 = inl(acpi_gbl_FADT.xpm_timer_block.address);
-+ kt1 = ktime_get_real();
- acpi_idle_do_entry(cx);
-- t2 = inl(acpi_gbl_FADT.xpm_timer_block.address);
-+ kt2 = ktime_get_real();
-+ idle_time = ktime_to_us(ktime_sub(kt2, kt1));
-
- local_irq_enable();
- cx->usage++;
-
-- return ticks_elapsed_in_us(t1, t2);
-+ return idle_time;
- }
-
- /**
-@@ -891,8 +877,9 @@ static int acpi_idle_enter_simple(struct
- {
- struct acpi_processor *pr;
- struct acpi_processor_cx *cx = cpuidle_get_statedata(state);
-- u32 t1, t2;
-- int sleep_ticks = 0;
-+ ktime_t kt1, kt2;
-+ s64 idle_time;
-+ s64 sleep_ticks = 0;
-
- pr = __get_cpu_var(processors);
-
-@@ -925,18 +912,19 @@ static int acpi_idle_enter_simple(struct
- if (cx->type == ACPI_STATE_C3)
- ACPI_FLUSH_CPU_CACHE();
-
-- t1 = inl(acpi_gbl_FADT.xpm_timer_block.address);
-+ kt1 = ktime_get_real();
- /* Tell the scheduler that we are going deep-idle: */
- sched_clock_idle_sleep_event();
- acpi_idle_do_entry(cx);
-- t2 = inl(acpi_gbl_FADT.xpm_timer_block.address);
-+ kt2 = ktime_get_real();
-+ idle_time = ktime_to_us(ktime_sub(kt2, kt1));
-
- #if defined (CONFIG_GENERIC_TIME) && defined (CONFIG_X86)
- /* TSC could halt in idle, so notify users */
- if (tsc_halts_in_c(cx->type))
- mark_tsc_unstable("TSC halts in idle");;
- #endif
-- sleep_ticks = ticks_elapsed(t1, t2);
-+ sleep_ticks = us_to_pm_timer_ticks(idle_time);
-
- /* Tell the scheduler how much we idled: */
- sched_clock_idle_wakeup_event(sleep_ticks*PM_TIMER_TICK_NS);
-@@ -948,7 +936,7 @@ static int acpi_idle_enter_simple(struct
-
- acpi_state_timer_broadcast(pr, cx, 0);
- cx->time += sleep_ticks;
-- return ticks_elapsed_in_us(t1, t2);
-+ return idle_time;
- }
-
- static int c3_cpu_count;
-@@ -966,8 +954,10 @@ static int acpi_idle_enter_bm(struct cpu
- {
- struct acpi_processor *pr;
- struct acpi_processor_cx *cx = cpuidle_get_statedata(state);
-- u32 t1, t2;
-- int sleep_ticks = 0;
-+ ktime_t kt1, kt2;
-+ s64 idle_time;
-+ s64 sleep_ticks = 0;
-+
-
- pr = __get_cpu_var(processors);
-
-@@ -1034,9 +1024,10 @@ static int acpi_idle_enter_bm(struct cpu
- ACPI_FLUSH_CPU_CACHE();
- }
-
-- t1 = inl(acpi_gbl_FADT.xpm_timer_block.address);
-+ kt1 = ktime_get_real();
- acpi_idle_do_entry(cx);
-- t2 = inl(acpi_gbl_FADT.xpm_timer_block.address);
-+ kt2 = ktime_get_real();
-+ idle_time = ktime_to_us(ktime_sub(kt2, kt1));
-
- /* Re-enable bus master arbitration */
- if (pr->flags.bm_check && pr->flags.bm_control) {
-@@ -1051,7 +1042,7 @@ static int acpi_idle_enter_bm(struct cpu
- if (tsc_halts_in_c(ACPI_STATE_C3))
- mark_tsc_unstable("TSC halts in idle");
- #endif
-- sleep_ticks = ticks_elapsed(t1, t2);
-+ sleep_ticks = us_to_pm_timer_ticks(idle_time);
- /* Tell the scheduler how much we idled: */
- sched_clock_idle_wakeup_event(sleep_ticks*PM_TIMER_TICK_NS);
-
-@@ -1062,7 +1053,7 @@ static int acpi_idle_enter_bm(struct cpu
-
- acpi_state_timer_broadcast(pr, cx, 0);
- cx->time += sleep_ticks;
-- return ticks_elapsed_in_us(t1, t2);
-+ return idle_time;
- }
-
- struct cpuidle_driver acpi_idle_driver = {
projects / thirdparty / kernel / stable-queue.git / commitdiff
