Subject: ACPI: Use clocksource to get the C-state time instead of ACPI PM timer
From: Zhao Yakui <yakui.zhao@xxxxxxxxx>
On most boxes the ACPI PM timer is 24-bit counter that runs on 3.579545MHz
clock. In such case the max C-state sleep time should be less than 4687ms when
it is used to record C2/C3 duration time.
But on some boxes the max C-state sleep time is more than 4687ms. In such
case the overflow happens and the C-state duration time can't be counted
accurately.
Use clocksource to get the C-state time instead of ACPI PM timer
Based on the Venki's suggestion the function of ktime_get_real is used as it
is unnecessary to use the monotonic time.
Signed-off-by: Yakui Zhao <yakui.zhao@xxxxxxxxx>
Signed-off-by: Alexs Shi <alex.shi@xxxxxxxxx>
Signed-off-by: Shaohua Li <shaohua.li@xxxxxxxxx>
Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@xxxxxxxxx>
---
drivers/acpi/processor_idle.c | 68 +++++++++++++++++++++++++-----------------
1 file changed, 42 insertions(+), 26 deletions(-)
Index: linux-2.6/drivers/acpi/processor_idle.c
===================================================================
--- linux-2.6.orig/drivers/acpi/processor_idle.c
+++ linux-2.6/drivers/acpi/processor_idle.c
@@ -397,8 +397,8 @@ static void acpi_processor_idle(void)
struct acpi_processor_cx *cx = NULL;
struct acpi_processor_cx *next_state = NULL;
int sleep_ticks = 0;
- u32 t1, t2 = 0;
-
+ ktime_t kt1, kt2;
+ u64 sleep_interval;
/*
* Interrupts must be disabled during bus mastering calculations and
* for C2/C3 transitions.
@@ -543,23 +543,26 @@ static void acpi_processor_idle(void)
break;
case ACPI_STATE_C2:
- /* Get start time (ticks) */
- 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();
/* Invoke C2 */
acpi_state_timer_broadcast(pr, cx, 1);
acpi_cstate_enter(cx);
/* Get end time (ticks) */
- t2 = inl(acpi_gbl_FADT.xpm_timer_block.address);
-
+ kt2 = ktime_get_real();
#if defined (CONFIG_GENERIC_TIME) && defined (CONFIG_X86)
/* TSC halts in C2, so notify users */
if (tsc_halts_in_c(ACPI_STATE_C2))
mark_tsc_unstable("possible TSC halt in C2");
#endif
+ /*
+ * Use the function of ktime_sub to get the time interval and
+ * then convert it to microsecond
+ */
+ sleep_interval = ktime_to_us(ktime_sub(kt2, kt1));
/* Compute time (ticks) that we were actually asleep */
- sleep_ticks = ticks_elapsed(t1, t2);
+ sleep_ticks = US_TO_PM_TIMER_TICKS(sleep_interval);
/* Tell the scheduler how much we idled: */
sched_clock_idle_wakeup_event(sleep_ticks*PM_TIMER_TICK_NS);
@@ -605,13 +608,13 @@ static void acpi_processor_idle(void)
}
/* Get start time (ticks) */
- t1 = inl(acpi_gbl_FADT.xpm_timer_block.address);
+ kt1 = ktime_get_real();
/* Invoke C3 */
/* Tell the scheduler that we are going deep-idle: */
sched_clock_idle_sleep_event();
acpi_cstate_enter(cx);
/* Get end time (ticks) */
- t2 = inl(acpi_gbl_FADT.xpm_timer_block.address);
+ kt2 = ktime_get_real();
if (pr->flags.bm_check && pr->flags.bm_control) {
/* Enable bus master arbitration */
atomic_dec(&c3_cpu_count);
@@ -623,8 +626,13 @@ static void acpi_processor_idle(void)
if (tsc_halts_in_c(ACPI_STATE_C3))
mark_tsc_unstable("TSC halts in C3");
#endif
+ /*
+ * Use the function of ktime_sub to get the time interval
+ * and convert it to microsecond.
+ */
+ sleep_interval = ktime_to_us(ktime_sub(kt2, kt1));
/* Compute time (ticks) that we were actually asleep */
- sleep_ticks = ticks_elapsed(t1, t2);
+ sleep_ticks = US_TO_PM_TIMER_TICKS(sleep_interval);
/* Tell the scheduler how much we idled: */
sched_clock_idle_wakeup_event(sleep_ticks*PM_TIMER_TICK_NS);
@@ -1455,7 +1463,8 @@ 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;
+ u64 sleep_interval;
struct acpi_processor *pr;
struct acpi_processor_cx *cx = cpuidle_get_statedata(state);
@@ -1476,14 +1485,18 @@ static int acpi_idle_enter_c1(struct cpu
if (pr->flags.bm_check)
acpi_idle_update_bm_rld(pr, cx);
- 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();
local_irq_enable();
cx->usage++;
-
- return ticks_elapsed_in_us(t1, t2);
+ /*
+ * Use the ktime_sub to get the time interval and then convert
+ * it to microseconds
+ */
+ sleep_interval = ktime_to_us(ktime_sub(kt2, kt1));
+ return sleep_interval;
}
/**
@@ -1496,7 +1509,8 @@ static int acpi_idle_enter_simple(struct
{
struct acpi_processor *pr;
struct acpi_processor_cx *cx = cpuidle_get_statedata(state);
- u32 t1, t2;
+ ktime_t kt1, kt2;
+ u64 sleep_interval;
int sleep_ticks = 0;
pr = __get_cpu_var(processors);
@@ -1533,18 +1547,19 @@ 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();
#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_interval = ktime_to_us(ktime_sub(kt2, kt1));
+ sleep_ticks = US_TO_PM_TIMER_TICKS(sleep_interval);
/* Tell the scheduler how much we idled: */
sched_clock_idle_wakeup_event(sleep_ticks*PM_TIMER_TICK_NS);
@@ -1556,7 +1571,7 @@ 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 sleep_interval;
}
static int c3_cpu_count;
@@ -1574,7 +1589,8 @@ static int acpi_idle_enter_bm(struct cpu
{
struct acpi_processor *pr;
struct acpi_processor_cx *cx = cpuidle_get_statedata(state);
- u32 t1, t2;
+ ktime_t kt1, kt2;
+ u64 sleep_interval;
int sleep_ticks = 0;
pr = __get_cpu_var(processors);
@@ -1643,10 +1659,9 @@ static int acpi_idle_enter_bm(struct cpu
} else if (!pr->flags.bm_check) {
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();
/* Re-enable bus master arbitration */
if (pr->flags.bm_check && pr->flags.bm_control) {
@@ -1661,7 +1676,8 @@ 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_interval = ktime_to_us(ktime_sub(kt2, kt1));
+ sleep_ticks = US_TO_PM_TIMER_TICKS(sleep_interval);
/* Tell the scheduler how much we idled: */
sched_clock_idle_wakeup_event(sleep_ticks*PM_TIMER_TICK_NS);
@@ -1672,7 +1688,7 @@ 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 sleep_interval;
}
struct cpuidle_driver acpi_idle_driver = {
--
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