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| author | Jason Baron <jbaron@akamai.com> | 2017-10-06 13:19:45 -0400 |
|---|---|---|
| committer | Rafael J. Wysocki <rafael.j.wysocki@intel.com> | 2017-10-11 02:02:16 +0200 |
| commit | 0563bb7ba67eec7a87a9ccc04b80bb59de26c319 (patch) | |
| tree | dd90a616853afceca5532c2359a683a25206f38d /drivers/idle | |
| parent | f187851b9b4a76952b1158b86434563dd2031103 (diff) | |
| download | lwn-0563bb7ba67eec7a87a9ccc04b80bb59de26c319.tar.gz lwn-0563bb7ba67eec7a87a9ccc04b80bb59de26c319.zip | |
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>
Diffstat (limited to 'drivers/idle')
| -rw-r--r-- | drivers/idle/intel_idle.c | 16 |
1 files changed, 11 insertions, 5 deletions
diff --git a/drivers/idle/intel_idle.c b/drivers/idle/intel_idle.c index 5dc7ea4b6bc4..5db5e3176f6a 100644 --- a/drivers/idle/intel_idle.c +++ b/drivers/idle/intel_idle.c @@ -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; |