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Message-id: <alpine.LFD.2.00.0901192148370.21686@localhost.localdomain>
Date: Mon, 19 Jan 2009 21:52:54 -0500 (EST)
From: Len Brown <lenb@...nel.org>
To: Zhao Yakui <yakui.zhao@...el.com>
Cc: linux-acpi@...r.kernel.org,
Venkatesh Pallipadi <venkatesh.pallipadi@...el.com>,
Thomas Gleixner <tglx@...utronix.de>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [RESEND] [PATCH] : ACPI : Use clocksource to get the C-state time
instead of ACPI PM timer
Adding Thomas Gleixner and LKML to this thread.
Thomas,
Basically we're now faced with the possibility
of cores left idle for longer than the 24-bit
pm-timer can count (4.6 seconds), we we can't
hard code use of that timer for
C-state residency accounting.
Is ktime_get_real() the right interface to use?
thanks,
-Len
On Tue, 13 Jan 2009, Zhao Yakui wrote:
> Subject: ACPI: Use clocksource to get the C-state time instead of ACPI PM timer
> From: Zhao Yakui <yakui.zhao@...el.com>
>
> 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@...el.com>
> Signed-off-by: Alexs Shi <alex.shi@...el.com>
> Signed-off-by: Shaohua Li <shaohua.li@...el.com>
> Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@...el.com>
> ---
> 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 = {
>
>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-acpi" in
> the body of a message to majordomo@...r.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
>
> Subject: ACPI: Use clocksource to get the C-state time instead of ACPI PM timer
> From: Zhao Yakui <yakui.zhao@...el.com>
>
> 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@...el.com>
> Signed-off-by: Alexs Shi <alex.shi@...el.com>
> Signed-off-by: Shaohua Li <shaohua.li@...el.com>
> Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@...el.com>
> ---
> 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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