[PATCH 0/2] cpuidle: Remove unnecessary TIF_NR_POLLING clear/TIF_NEED_RESCHED folding

[PATCH 0/2] cpuidle: Remove unnecessary TIF_NR_POLLING clear/TIF_NEED_RESCHED folding

[Frederic Weisbecker]

Hi Rafael,

Those are cpuidle patches that you acked from a previous posting. I
figured they would be best routed through you so I'm reposting those
strict cpuidle bits from the series.

Thanks.

Frederic Weisbecker (2):
  cpuidle: Remove unnecessary current_clr_polling_and_test() from
    haltpoll
  cpuidle: Remove unnecessary current_clr_polling() on poll_idle()

 drivers/cpuidle/cpuidle-haltpoll.c | 5 +----
 drivers/cpuidle/poll_state.c       | 2 --
 2 files changed, 1 insertion(+), 6 deletions(-)

-- 
2.42.1

[PATCH 1/2] cpuidle: Remove unnecessary current_clr_polling_and_test() from haltpoll

[Frederic Weisbecker]

When cpuidle drivers ->enter() callback are called, the TIF_NR_POLLING
flag is cleared already and TIF_NEED_RESCHED checked by call_cpuidle().

Therefore calling current_clr_polling_and_test() is redundant here and
further setting of TIF_NEED_RESCHED will result in an IPI and thus an
idle loop exit. This call can be safely removed.

Cc: Marcelo Tosatti <mtosatti@redhat.com>
Acked-by: Rafael J. Wysocki <rafael@kernel.org>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
---
 drivers/cpuidle/cpuidle-haltpoll.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/drivers/cpuidle/cpuidle-haltpoll.c b/drivers/cpuidle/cpuidle-haltpoll.c
index e66df22f9695..b641bc535102 100644
--- a/drivers/cpuidle/cpuidle-haltpoll.c
+++ b/drivers/cpuidle/cpuidle-haltpoll.c
@@ -28,11 +28,8 @@ static enum cpuhp_state haltpoll_hp_state;
 static int default_enter_idle(struct cpuidle_device *dev,
 			      struct cpuidle_driver *drv, int index)
 {
-	if (current_clr_polling_and_test()) {
-		local_irq_enable();
-		return index;
-	}
 	arch_cpu_idle();
+
 	return index;
 }
 
-- 
2.42.1

[PATCH 2/2] cpuidle: Remove unnecessary current_clr_polling() on poll_idle()

[Frederic Weisbecker]

There is no point in clearing TIF_NR_POLLING and folding TIF_NEED_RESCHED
upon poll_idle() exit because cpuidle_idle_call() is going to set again
TIF_NR_POLLING anyway. Also if TIF_NEED_RESCHED is set, it will be
folded and TIF_NR_POLLING will be cleared at the end of do_idle().

Acked-by: Rafael J. Wysocki <rafael@kernel.org>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
---
 drivers/cpuidle/poll_state.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/drivers/cpuidle/poll_state.c b/drivers/cpuidle/poll_state.c
index 9b6d90a72601..d5cb3eb85a54 100644
--- a/drivers/cpuidle/poll_state.c
+++ b/drivers/cpuidle/poll_state.c
@@ -40,8 +40,6 @@ static int __cpuidle poll_idle(struct cpuidle_device *dev,
 	}
 	raw_local_irq_disable();
 
-	current_clr_polling();
-
 	return index;
 }
 
-- 
2.42.1

Re: [PATCH 2/2] cpuidle: Remove unnecessary current_clr_polling() on poll_idle()

[Frederic Weisbecker]

Le Mon, Nov 13, 2023 at 05:03:26PM -0500, Frederic Weisbecker a écrit :
> There is no point in clearing TIF_NR_POLLING and folding TIF_NEED_RESCHED
> upon poll_idle() exit because cpuidle_idle_call() is going to set again
> TIF_NR_POLLING anyway. Also if TIF_NEED_RESCHED is set, it will be
> folded and TIF_NR_POLLING will be cleared at the end of do_idle().
> 
> Acked-by: Rafael J. Wysocki <rafael@kernel.org>
> Signed-off-by: Frederic Weisbecker <frederic@kernel.org>

Please discard this one, I'm taking a new way to deal with that.

Thanks.

> ---
>  drivers/cpuidle/poll_state.c | 2 --
>  1 file changed, 2 deletions(-)
> 
> diff --git a/drivers/cpuidle/poll_state.c b/drivers/cpuidle/poll_state.c
> index 9b6d90a72601..d5cb3eb85a54 100644
> --- a/drivers/cpuidle/poll_state.c
> +++ b/drivers/cpuidle/poll_state.c
> @@ -40,8 +40,6 @@ static int __cpuidle poll_idle(struct cpuidle_device *dev,
>  	}
>  	raw_local_irq_disable();
>  
> -	current_clr_polling();
> -
>  	return index;
>  }
>  
> -- 
> 2.42.1
>