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@xxxxxxxxxxxx] >Sent: 2009年4月23日 15:21 >To: linux-kernel@xxxxxxxxxxxxxxx; stable@xxxxxxxxxx >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@xxxxxxxxxxxxxxxxxxxx; akpm@xxxxxxxxxxxxxxxxxxxx; >alan@xxxxxxxxxxxxxxxxxxx; Len Brown; linux-acpi@xxxxxxxxxxxxxxx; 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@xxxxxxxxx> > >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@xxxxxxxxx> >Tested-by: Alex Shi <alex.shi@xxxxxxxxx> >Signed-off-by: Alex Shi <alex.shi@xxxxxxxxx> >Signed-off-by: Yakui.zhao <yakui.zhao@xxxxxxxxx> >Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> >Signed-off-by: Len Brown <len.brown@xxxxxxxxx> >Signed-off-by: Chris Wright <chrisw@xxxxxxxxxxxx> >--- > 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 = { ?韬{.n?????%??檩??w?{.n???{饼??Ф?塄}?财??j:+v?? ? ???2??璀??摺?囤??z夸z罐?+?????w棹f
