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intel_idle: replace conditionals with static_cpu_has(X86_FEATURE_ARAT) 

If the 'arat' cpu flag is set, then the conditionals in intel_idle() that
guard calling tick_broadcast_enter()/exit() will never be true. Use
static_cpu_has(X86_FEATURE_ARAT) to create a fast path to replace
the conditional.

Signed-off-by: Jason Baron <jbaron@akamai.com>
Acked-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This commit is contained in:
Jason Baron 2017-10-06 13:19:45 -04:00 committed by Rafael J. Wysocki
parent f187851b9b
commit 0563bb7ba6
1 changed files with 11 additions and 5 deletions
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16
drivers/idle/intel_idle.c
View File

@ -913,8 +913,7 @@ static __cpuidle int intel_idle(struct cpuidle_device *dev,
struct cpuidle_state *state = &drv->states[index];
unsigned long eax = flg2MWAIT(state->flags);
unsigned int cstate;
cstate = (((eax) >> MWAIT_SUBSTATE_SIZE) & MWAIT_CSTATE_MASK) + 1;
bool uninitialized_var(tick);
/*
* NB: if CPUIDLE_FLAG_TLB_FLUSHED is set, this idle transition
@ -923,12 +922,19 @@ static __cpuidle int intel_idle(struct cpuidle_device *dev,
* useful with this knowledge.
*/
if (!(lapic_timer_reliable_states & (1 << (cstate))))
tick_broadcast_enter();
if (!static_cpu_has(X86_FEATURE_ARAT)) {
cstate = (((eax) >> MWAIT_SUBSTATE_SIZE) &
MWAIT_CSTATE_MASK) + 1;
tick = false;
if (!(lapic_timer_reliable_states & (1 << (cstate)))) {
tick = true;
tick_broadcast_enter();
}
}
mwait_idle_with_hints(eax, ecx);
if (!(lapic_timer_reliable_states & (1 << (cstate))))
if (!static_cpu_has(X86_FEATURE_ARAT) && tick)
tick_broadcast_exit();
return index;