Messages in this thread | | | Date | Mon, 23 Nov 2020 14:46:18 +0100 | From | Peter Zijlstra <> | Subject | Re: [PATCH 2/2] intel_idle: Fix intel_idle() vs tracing |
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On Mon, Nov 23, 2020 at 11:26:39AM +0100, Rafael J. Wysocki wrote: > On Fri, Nov 20, 2020 at 12:50 PM Peter Zijlstra <peterz@infradead.org> wrote: > > > > cpuidle->enter() callbacks should not call into tracing because RCU > > has already been disabled. Instead of doing the broadcast thing > > itself, simply advertise to the cpuidle core that those states stop > > the timer. > > > > Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> > > --- > > drivers/idle/intel_idle.c | 37 ++++++++++++++++++++----------------- > > 1 file changed, 20 insertions(+), 17 deletions(-) > > > > --- a/drivers/idle/intel_idle.c > > +++ b/drivers/idle/intel_idle.c > > @@ -126,26 +126,9 @@ static __cpuidle int intel_idle(struct c > > struct cpuidle_state *state = &drv->states[index]; > > unsigned long eax = flg2MWAIT(state->flags); > > unsigned long ecx = 1; /* break on interrupt flag */ > > - bool tick; > > - > > - if (!static_cpu_has(X86_FEATURE_ARAT)) { > > - /* > > - * Switch over to one-shot tick broadcast if the target C-state > > - * is deeper than C1. > > - */ > > - if ((eax >> MWAIT_SUBSTATE_SIZE) & MWAIT_CSTATE_MASK) { > > - tick = true; > > - tick_broadcast_enter(); > > - } else { > > - tick = false; > > - } > > - } > > > > mwait_idle_with_hints(eax, ecx); > > > > - if (!static_cpu_has(X86_FEATURE_ARAT) && tick) > > - tick_broadcast_exit(); > > - > > return index; > > } > > > > @@ -1460,6 +1443,23 @@ static bool __init intel_idle_verify_cst > > return true; > > } > > > > +static bool __init intel_idle_state_needs_timer_stop(struct cpuidle_state *state) > > +{ > > + unsigned long eax = flg2MWAIT(state->flags); > > + > > + if (boot_cpu_has(X86_FEATURE_ARAT)) > > + return false; > > + > > + /* > > + * Switch over to one-shot tick broadcast if the target C-state > > + * is deeper than C1. > > + */ > > + if ((eax >> MWAIT_SUBSTATE_SIZE) & MWAIT_CSTATE_MASK) > > + return true; > > + > > + return false; > > +} > > + > > static void __init intel_idle_init_cstates_icpu(struct cpuidle_driver *drv) > > { > > int cstate; > > @@ -1507,6 +1507,9 @@ static void __init intel_idle_init_cstat > > !(cpuidle_state_table[cstate].flags & CPUIDLE_FLAG_ALWAYS_ENABLE))) > > drv->states[drv->state_count].flags |= CPUIDLE_FLAG_OFF; > > > > + if (intel_idle_state_needs_timer_stop(&drv->states[drv->state_count])) > > + drv->states[drv->state_count].flags |= CPUIDLE_FLAG_TIMER_STOP; > > + > > drv->state_count++; > > } > > This doesn't cover the ACPI case AFAICS.
aa6b43d57f99 ("ACPI: processor: Use CPUIDLE_FLAG_TIMER_STOP")
did that, no?
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