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SubjectRE: [patch 012/100] acpi: fix of pmtimer overflow that make Cx states time incorrect
Update: 
Len Brown's patch may fix this bug.
http://bugzilla.kernel.org/show_bug.cgi?id=13087#c41

Alex

>-----Original Message-----
>From: Shi, Alex
>Sent: 2009年4月23日 17:25
>To: 'Chris Wright'; linux-kernel@vger.kernel.org; stable@kernel.org
>Cc: Justin Forbes; Zwane Mwaikambo; Theodore Ts'o; Randy Dunlap; Dave Jones;
>Chuck Wolber; Chris Wedgwood; Michael Krufky; Chuck Ebbert; Domenico Andreoli;
>Willy Tarreau; Rodrigo Rubira Branco; Jake Edge; Eugene Teo;
>torvalds@linux-foundation.org; akpm@linux-foundation.org;
>alan@lxorguk.ukuu.org.uk; Len Brown; linux-acpi@vger.kernel.org; Pallipadi,
>Venkatesh; Zhao, Yakui; Brown, Len
>Subject: RE: [patch 012/100] acpi: fix of pmtimer overflow that make Cx states
>time incorrect
>
>It was reported make some latop booting hang. and is not root caused now. :(
>http://bugzilla.kernel.org/show_bug.cgi?id=13087
>
>Alex
>>-----Original Message-----
>>From: Chris Wright [mailto:chrisw@sous-sol.org]
>>Sent: 2009年4月23日 15:21
>>To: linux-kernel@vger.kernel.org; stable@kernel.org
>>Cc: Justin Forbes; Zwane Mwaikambo; Theodore Ts'o; Randy Dunlap; Dave Jones;
>>Chuck Wolber; Chris Wedgwood; Michael Krufky; Chuck Ebbert; Domenico Andreoli;
>>Willy Tarreau; Rodrigo Rubira Branco; Jake Edge; Eugene Teo;
>>torvalds@linux-foundation.org; akpm@linux-foundation.org;
>>alan@lxorguk.ukuu.org.uk; Len Brown; linux-acpi@vger.kernel.org; Shi, Alex;
>>Pallipadi, Venkatesh; Zhao, Yakui; Brown, Len
>>Subject: [patch 012/100] acpi: fix of pmtimer overflow that make Cx states time
>>incorrect
>>
>>-stable review patch. If anyone has any objections, please let us know.
>>---------------------
>>
>>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 = {

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