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Date: Tue, 15 Sep 2020 18:26:52 +0200
From: "Rafael J. Wysocki" <rafael@...nel.org>
To: Peter Zijlstra <peterz@...radead.org>
Cc: "Rafael J. Wysocki" <rjw@...ysocki.net>,
Borislav Petkov <bp@...en8.de>,
"the arch/x86 maintainers" <x86@...nel.org>,
Tony Luck <tony.luck@...el.com>, Len Brown <lenb@...nel.org>,
Daniel Lezcano <daniel.lezcano@...aro.org>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
Linux PM <linux-pm@...r.kernel.org>,
Ulf Hansson <ulf.hansson@...aro.org>,
"Paul E. McKenney" <paulmck@...nel.org>,
Thomas Gleixner <tglx@...utronix.de>,
Naresh Kamboju <naresh.kamboju@...aro.org>
Subject: Re: [RFC][PATCH 1/4] acpi: Use CPUIDLE_FLAG_TIMER_STOP
On Tue, Sep 15, 2020 at 12:44 PM Peter Zijlstra <peterz@...radead.org> wrote:
>
> Make acpi_processor_idle use the common broadcast code, there's no
> reason not to. This also removes some RCU usage after
> rcu_idle_enter().
>
> Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
The whole series looks good to me, so please feel free to add
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
to all of the four patches.
Alternatively, please let me know if you want me to take the patches.
> ---
> drivers/acpi/processor_idle.c | 49 +++++++++++++-----------------------------
> 1 file changed, 16 insertions(+), 33 deletions(-)
>
> --- a/drivers/acpi/processor_idle.c
> +++ b/drivers/acpi/processor_idle.c
> @@ -161,18 +161,10 @@ static void lapic_timer_propagate_broadc
> }
>
> /* Power(C) State timer broadcast control */
> -static void lapic_timer_state_broadcast(struct acpi_processor *pr,
> - struct acpi_processor_cx *cx,
> - int broadcast)
> -{
> - int state = cx - pr->power.states;
> -
> - if (state >= pr->power.timer_broadcast_on_state) {
> - if (broadcast)
> - tick_broadcast_enter();
> - else
> - tick_broadcast_exit();
> - }
> +static bool lapic_timer_needs_broadcast(struct acpi_processor *pr,
> + struct acpi_processor_cx *cx)
> +{
> + return cx - pr->power.states >= pr->power.timer_broadcast_on_state;
> }
>
> #else
> @@ -180,9 +172,9 @@ static void lapic_timer_state_broadcast(
> static void lapic_timer_check_state(int state, struct acpi_processor *pr,
> struct acpi_processor_cx *cstate) { }
> static void lapic_timer_propagate_broadcast(struct acpi_processor *pr) { }
> -static void lapic_timer_state_broadcast(struct acpi_processor *pr,
> - struct acpi_processor_cx *cx,
> - int broadcast)
> +
> +static bool lapic_timer_needs_broadcast(struct acpi_processor *pr,
> + struct acpi_processor_cx *cx)
> {
> }
>
> @@ -568,21 +560,13 @@ static DEFINE_RAW_SPINLOCK(c3_lock);
> * acpi_idle_enter_bm - enters C3 with proper BM handling
> * @pr: Target processor
> * @cx: Target state context
> - * @timer_bc: Whether or not to change timer mode to broadcast
> */
> static void acpi_idle_enter_bm(struct acpi_processor *pr,
> - struct acpi_processor_cx *cx, bool timer_bc)
> + struct acpi_processor_cx *cx)
> {
> acpi_unlazy_tlb(smp_processor_id());
>
> /*
> - * Must be done before busmaster disable as we might need to
> - * access HPET !
> - */
> - if (timer_bc)
> - lapic_timer_state_broadcast(pr, cx, 1);
> -
> - /*
> * disable bus master
> * bm_check implies we need ARB_DIS
> * bm_control implies whether we can do ARB_DIS
> @@ -609,9 +593,6 @@ static void acpi_idle_enter_bm(struct ac
> c3_cpu_count--;
> raw_spin_unlock(&c3_lock);
> }
> -
> - if (timer_bc)
> - lapic_timer_state_broadcast(pr, cx, 0);
> }
>
> static int acpi_idle_enter(struct cpuidle_device *dev,
> @@ -630,7 +611,7 @@ static int acpi_idle_enter(struct cpuidl
> cx = per_cpu(acpi_cstate[index], dev->cpu);
> } else if (cx->type == ACPI_STATE_C3 && pr->flags.bm_check) {
> if (cx->bm_sts_skip || !acpi_idle_bm_check()) {
> - acpi_idle_enter_bm(pr, cx, true);
> + acpi_idle_enter_bm(pr, cx);
> return index;
> } else if (drv->safe_state_index >= 0) {
> index = drv->safe_state_index;
> @@ -642,15 +623,11 @@ static int acpi_idle_enter(struct cpuidl
> }
> }
>
> - lapic_timer_state_broadcast(pr, cx, 1);
> -
> if (cx->type == ACPI_STATE_C3)
> ACPI_FLUSH_CPU_CACHE();
>
> acpi_idle_do_entry(cx);
>
> - lapic_timer_state_broadcast(pr, cx, 0);
> -
> return index;
> }
>
> @@ -666,7 +643,7 @@ static int acpi_idle_enter_s2idle(struct
> return 0;
>
> if (pr->flags.bm_check) {
> - acpi_idle_enter_bm(pr, cx, false);
> + acpi_idle_enter_bm(pr, cx);
> return 0;
> } else {
> ACPI_FLUSH_CPU_CACHE();
> @@ -682,6 +659,7 @@ static int acpi_processor_setup_cpuidle_
> {
> int i, count = ACPI_IDLE_STATE_START;
> struct acpi_processor_cx *cx;
> + struct cpuidle_state *state;
>
> if (max_cstate == 0)
> max_cstate = 1;
> @@ -694,6 +672,11 @@ static int acpi_processor_setup_cpuidle_
>
> per_cpu(acpi_cstate[count], dev->cpu) = cx;
>
> + if (lapic_timer_needs_broadcast(pr, cx)) {
> + state = &acpi_idle_driver.states[count];
> + state->flags |= CPUIDLE_FLAG_TIMER_STOP;
> + }
> +
> count++;
> if (count == CPUIDLE_STATE_MAX)
> break;
>
>
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