From: Ulf Hansson <ulf.hansson@linaro.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>,
Borislav Petkov <bp@alien8.de>,
x86@kernel.org, Tony Luck <tony.luck@intel.com>,
Len Brown <lenb@kernel.org>,
Daniel Lezcano <daniel.lezcano@linaro.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
ACPI Devel Maling List <linux-acpi@vger.kernel.org>,
Linux PM <linux-pm@vger.kernel.org>,
"Paul E. McKenney" <paulmck@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Naresh Kamboju <naresh.kamboju@linaro.org>
Subject: Re: [RFC][PATCH 3/4] cpuidle: Allow cpuidle drivers to take over RCU-idle
Date: Tue, 15 Sep 2020 15:20:27 +0200 [thread overview]
Message-ID: <CAPDyKFpku8oybzyDpSBU0JEkdaEFkadA9P=QLcB-RkQtVhTe8A@mail.gmail.com> (raw)
In-Reply-To: <20200915103806.411374792@infradead.org>
On Tue, 15 Sep 2020 at 12:44, Peter Zijlstra <peterz@infradead.org> wrote:
>
> Some drivers have to do significant work, some of which relies on RCU
> still being active. Instead of using RCU_NONIDLE in the drivers and
> flipping RCU back on, allow drivers to take over RCU-idle duty.
>
> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>
Kind regards
Uffe
> ---
> drivers/cpuidle/cpuidle.c | 15 ++++++++++-----
> include/linux/cpuidle.h | 1 +
> 2 files changed, 11 insertions(+), 5 deletions(-)
>
> --- a/drivers/cpuidle/cpuidle.c
> +++ b/drivers/cpuidle/cpuidle.c
> @@ -138,6 +138,7 @@ static void enter_s2idle_proper(struct c
> struct cpuidle_device *dev, int index)
> {
> ktime_t time_start, time_end;
> + struct cpuidle_state *target_state = &drv->states[index];
>
> time_start = ns_to_ktime(local_clock());
>
> @@ -153,8 +154,9 @@ static void enter_s2idle_proper(struct c
> * suspended is generally unsafe.
> */
> stop_critical_timings();
> - rcu_idle_enter();
> - drv->states[index].enter_s2idle(dev, drv, index);
> + if (!(target_state->flags & CPUIDLE_FLAG_RCU_IDLE))
> + rcu_idle_enter();
> + target_state->enter_s2idle(dev, drv, index);
> if (WARN_ON_ONCE(!irqs_disabled()))
> local_irq_disable();
> /*
> @@ -162,7 +164,8 @@ static void enter_s2idle_proper(struct c
> * first CPU executing it calls functions containing RCU read-side
> * critical sections, so tell RCU about that.
> */
> - rcu_idle_exit();
> + if (!(target_state->flags & CPUIDLE_FLAG_RCU_IDLE))
> + rcu_idle_exit();
> tick_unfreeze();
> start_critical_timings();
>
> @@ -239,9 +242,11 @@ int cpuidle_enter_state(struct cpuidle_d
> time_start = ns_to_ktime(local_clock());
>
> stop_critical_timings();
> - rcu_idle_enter();
> + if (!(target_state->flags & CPUIDLE_FLAG_RCU_IDLE))
> + rcu_idle_enter();
> entered_state = target_state->enter(dev, drv, index);
> - rcu_idle_exit();
> + if (!(target_state->flags & CPUIDLE_FLAG_RCU_IDLE))
> + rcu_idle_exit();
> start_critical_timings();
>
> sched_clock_idle_wakeup_event();
> --- a/include/linux/cpuidle.h
> +++ b/include/linux/cpuidle.h
> @@ -82,6 +82,7 @@ struct cpuidle_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 */
>
> struct cpuidle_device_kobj;
> struct cpuidle_state_kobj;
>
>
next prev parent reply other threads:[~2020-09-15 13:51 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-15 10:31 [RFC][PATCH 0/4] Fix up ACPI processor idle vs RCU Peter Zijlstra
2020-09-15 10:31 ` [RFC][PATCH 1/4] acpi: Use CPUIDLE_FLAG_TIMER_STOP Peter Zijlstra
2020-09-15 16:26 ` Rafael J. Wysocki
2020-09-16 15:42 ` peterz
2020-09-16 16:01 ` Borislav Petkov
2020-09-16 17:38 ` Rafael J. Wysocki
2020-09-16 17:38 ` Rafael J. Wysocki
2020-09-22 3:26 ` Guenter Roeck
2020-09-22 19:03 ` Rafael J. Wysocki
2020-09-15 10:31 ` [RFC][PATCH 2/4] acpi: Use CPUIDLE_FLAG_TLB_FLUSHED Peter Zijlstra
2020-09-15 10:32 ` [RFC][PATCH 3/4] cpuidle: Allow cpuidle drivers to take over RCU-idle Peter Zijlstra
2020-09-15 13:20 ` Ulf Hansson [this message]
2020-09-15 10:32 ` [RFC][PATCH 4/4] acpi: Take over RCU-idle for C3-BM idle Peter Zijlstra
2020-09-21 9:12 ` Sven Joachim
2020-09-21 10:37 ` [PATCH] rcu/tree: Export rcu_idle_{enter,exit} to module Borislav Petkov
2020-09-21 12:15 ` Rafael J. Wysocki
2020-09-21 13:32 ` Paul E. McKenney
2020-09-21 13:38 ` Rafael J. Wysocki
2020-09-25 15:20 ` [RFC][PATCH 4/4] acpi: Take over RCU-idle for C3-BM idle Guenter Roeck
2020-09-25 15:24 ` Rafael J. Wysocki
2020-09-25 15:29 ` Paul E. McKenney
2020-09-15 18:31 ` [RFC][PATCH 0/4] Fix up ACPI processor idle vs RCU Borislav Petkov
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