[5/7] cpuidle: Introduce CPUIDLE_FLAG_POLLING_HARD
Commit Message
From: Peter Zijlstra <peterz@infradead.org>
Provide a way to tell the cpuidle core about states polling/monitoring
TIF_NEED_RESCHED on the hardware level, monitor/mwait users being the
only examples in use.
This will allow cpuidle core to manage TIF_NR_POLLING on behalf of all
kinds of TIF_NEED_RESCHED polling states while keeping a necessary
distinction for the governors between software loops polling on
TIF_NEED_RESCHED and hardware monitored writes to thread flags.
[fweisbec: _ Initialize flag from acpi_processor_setup_cstates() instead
of acpi_processor_setup_lpi_states(), as the latter seem to
be about arm64...
_ Rename CPUIDLE_FLAG_NO_IPI to CPUIDLE_FLAG_POLLING_HARD]
Not-yet-signed-off-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
---
drivers/acpi/processor_idle.c | 3 +++
drivers/idle/intel_idle.c | 5 ++++-
include/linux/cpuidle.h | 3 ++-
3 files changed, 9 insertions(+), 2 deletions(-)
Comments
On Fri, Nov 24, 2023 at 11:32 PM Frederic Weisbecker
<frederic@kernel.org> wrote:
>
> From: Peter Zijlstra <peterz@infradead.org>
>
> Provide a way to tell the cpuidle core about states polling/monitoring
> TIF_NEED_RESCHED on the hardware level, monitor/mwait users being the
> only examples in use.
>
> This will allow cpuidle core to manage TIF_NR_POLLING on behalf of all
> kinds of TIF_NEED_RESCHED polling states while keeping a necessary
> distinction for the governors between software loops polling on
> TIF_NEED_RESCHED and hardware monitored writes to thread flags.
>
> [fweisbec: _ Initialize flag from acpi_processor_setup_cstates() instead
> of acpi_processor_setup_lpi_states(), as the latter seem to
> be about arm64...
> _ Rename CPUIDLE_FLAG_NO_IPI to CPUIDLE_FLAG_POLLING_HARD]
>
> Not-yet-signed-off-by: Peter Zijlstra <peterz@infradead.org>
> Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
> ---
> drivers/acpi/processor_idle.c | 3 +++
> drivers/idle/intel_idle.c | 5 ++++-
> include/linux/cpuidle.h | 3 ++-
> 3 files changed, 9 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c
> index 3a34a8c425fe..a77a4d4b0dad 100644
> --- a/drivers/acpi/processor_idle.c
> +++ b/drivers/acpi/processor_idle.c
> @@ -814,6 +814,9 @@ static int acpi_processor_setup_cstates(struct acpi_processor *pr)
> if (cx->type != ACPI_STATE_C3)
> drv->safe_state_index = count;
> }
> +
> + if (cx->entry_method == ACPI_CSTATE_FFH)
> + state->flags |= CPUIDLE_FLAG_POLLING_HARD;
> /*
> * Halt-induced C1 is not good for ->enter_s2idle, because it
> * re-enables interrupts on exit. Moreover, C1 is generally not
> diff --git a/drivers/idle/intel_idle.c b/drivers/idle/intel_idle.c
> index 3e01a6b23e75..bc56624fe0b5 100644
> --- a/drivers/idle/intel_idle.c
> +++ b/drivers/idle/intel_idle.c
> @@ -1563,7 +1563,8 @@ static void __init intel_idle_init_cstates_acpi(struct cpuidle_driver *drv)
> if (cx->type > ACPI_STATE_C1)
> state->target_residency *= 3;
>
> - state->flags = MWAIT2flg(cx->address);
> + state->flags = MWAIT2flg(cx->address) | CPUIDLE_FLAG_POLLING_HARD;
> +
> if (cx->type > ACPI_STATE_C2)
> state->flags |= CPUIDLE_FLAG_TLB_FLUSHED;
>
> @@ -1836,6 +1837,8 @@ static bool __init intel_idle_verify_cstate(unsigned int mwait_hint)
>
> static void state_update_enter_method(struct cpuidle_state *state, int cstate)
> {
> + state->flags |= CPUIDLE_FLAG_POLLING_HARD;
> +
> if (state->flags & CPUIDLE_FLAG_INIT_XSTATE) {
> /*
> * Combining with XSTATE with IBRS or IRQ_ENABLE flags
> diff --git a/include/linux/cpuidle.h b/include/linux/cpuidle.h
> index 66b59868622c..873fdf200dc3 100644
> --- a/include/linux/cpuidle.h
> +++ b/include/linux/cpuidle.h
> @@ -78,13 +78,14 @@ struct cpuidle_state {
>
> /* Idle State Flags */
> #define CPUIDLE_FLAG_NONE (0x00)
> -#define CPUIDLE_FLAG_POLLING_SOFT BIT(0) /* polling state */
> +#define CPUIDLE_FLAG_POLLING_SOFT BIT(0) /* software need_resched() polling state */
> #define CPUIDLE_FLAG_COUPLED BIT(1) /* state applies to multiple cpus */
> #define CPUIDLE_FLAG_TIMER_STOP BIT(2) /* timer is stopped on this state */
> #define CPUIDLE_FLAG_UNUSABLE BIT(3) /* avoid using this state */
> #define CPUIDLE_FLAG_OFF BIT(4) /* disable this state by default */
> #define CPUIDLE_FLAG_TLB_FLUSHED BIT(5) /* idle-state flushes TLBs */
> #define CPUIDLE_FLAG_RCU_IDLE BIT(6) /* idle-state takes care of RCU */
> +#define CPUIDLE_FLAG_POLLING_HARD BIT(7) /* hardware need_resched() polling state */
Hardware need_resched() monitoring rather? This doesn't do what
"polling" usually means AFAICS.
>
> struct cpuidle_device_kobj;
> struct cpuidle_state_kobj;
> --
Le Tue, Dec 12, 2023 at 02:12:48PM +0100, Rafael J. Wysocki a écrit :
> > diff --git a/include/linux/cpuidle.h b/include/linux/cpuidle.h
> > index 66b59868622c..873fdf200dc3 100644
> > --- a/include/linux/cpuidle.h
> > +++ b/include/linux/cpuidle.h
> > @@ -78,13 +78,14 @@ struct cpuidle_state {
> >
> > /* Idle State Flags */
> > #define CPUIDLE_FLAG_NONE (0x00)
> > -#define CPUIDLE_FLAG_POLLING_SOFT BIT(0) /* polling state */
> > +#define CPUIDLE_FLAG_POLLING_SOFT BIT(0) /* software need_resched() polling state */
> > #define CPUIDLE_FLAG_COUPLED BIT(1) /* state applies to multiple cpus */
> > #define CPUIDLE_FLAG_TIMER_STOP BIT(2) /* timer is stopped on this state */
> > #define CPUIDLE_FLAG_UNUSABLE BIT(3) /* avoid using this state */
> > #define CPUIDLE_FLAG_OFF BIT(4) /* disable this state by default */
> > #define CPUIDLE_FLAG_TLB_FLUSHED BIT(5) /* idle-state flushes TLBs */
> > #define CPUIDLE_FLAG_RCU_IDLE BIT(6) /* idle-state takes care of RCU */
> > +#define CPUIDLE_FLAG_POLLING_HARD BIT(7) /* hardware need_resched() polling state */
>
> Hardware need_resched() monitoring rather? This doesn't do what
> "polling" usually means AFAICS.
Fair enough!
> >
> > struct cpuidle_device_kobj;
> > struct cpuidle_state_kobj;
> > --
@@ -814,6 +814,9 @@ static int acpi_processor_setup_cstates(struct acpi_processor *pr)
if (cx->type != ACPI_STATE_C3)
drv->safe_state_index = count;
}
+
+ if (cx->entry_method == ACPI_CSTATE_FFH)
+ state->flags |= CPUIDLE_FLAG_POLLING_HARD;
/*
* Halt-induced C1 is not good for ->enter_s2idle, because it
* re-enables interrupts on exit. Moreover, C1 is generally not
@@ -1563,7 +1563,8 @@ static void __init intel_idle_init_cstates_acpi(struct cpuidle_driver *drv)
if (cx->type > ACPI_STATE_C1)
state->target_residency *= 3;
- state->flags = MWAIT2flg(cx->address);
+ state->flags = MWAIT2flg(cx->address) | CPUIDLE_FLAG_POLLING_HARD;
+
if (cx->type > ACPI_STATE_C2)
state->flags |= CPUIDLE_FLAG_TLB_FLUSHED;
@@ -1836,6 +1837,8 @@ static bool __init intel_idle_verify_cstate(unsigned int mwait_hint)
static void state_update_enter_method(struct cpuidle_state *state, int cstate)
{
+ state->flags |= CPUIDLE_FLAG_POLLING_HARD;
+
if (state->flags & CPUIDLE_FLAG_INIT_XSTATE) {
/*
* Combining with XSTATE with IBRS or IRQ_ENABLE flags
@@ -78,13 +78,14 @@ struct cpuidle_state {
/* Idle State Flags */
#define CPUIDLE_FLAG_NONE (0x00)
-#define CPUIDLE_FLAG_POLLING_SOFT BIT(0) /* polling state */
+#define CPUIDLE_FLAG_POLLING_SOFT BIT(0) /* software need_resched() polling state */
#define CPUIDLE_FLAG_COUPLED BIT(1) /* state applies to multiple cpus */
#define CPUIDLE_FLAG_TIMER_STOP BIT(2) /* timer is stopped on this state */
#define CPUIDLE_FLAG_UNUSABLE BIT(3) /* avoid using this state */
#define CPUIDLE_FLAG_OFF BIT(4) /* disable this state by default */
#define CPUIDLE_FLAG_TLB_FLUSHED BIT(5) /* idle-state flushes TLBs */
#define CPUIDLE_FLAG_RCU_IDLE BIT(6) /* idle-state takes care of RCU */
+#define CPUIDLE_FLAG_POLLING_HARD BIT(7) /* hardware need_resched() polling state */
struct cpuidle_device_kobj;
struct cpuidle_state_kobj;