Messages in this thread | ![/](/images/icornerl.gif) | | From | "Rafael J. Wysocki" <> | Date | Tue, 12 Dec 2023 14:12:48 +0100 | Subject | Re: [PATCH 5/7] cpuidle: Introduce CPUIDLE_FLAG_POLLING_HARD |
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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; > --
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