From: Guenter Roeck <linux@roeck-us.net>
To: Peter Zijlstra <peterz@infradead.org>
Cc: rjw@rjwysocki.net, bp@alien8.de, x86@kernel.org,
tony.luck@intel.com, lenb@kernel.org, daniel.lezcano@linaro.org,
linux-kernel@vger.kernel.org, linux-acpi@vger.kernel.org,
linux-pm@vger.kernel.org, ulf.hansson@linaro.org,
paulmck@kernel.org, tglx@linutronix.de,
naresh.kamboju@linaro.org
Subject: Re: [RFC][PATCH 1/4] acpi: Use CPUIDLE_FLAG_TIMER_STOP
Date: Mon, 21 Sep 2020 20:26:51 -0700 [thread overview]
Message-ID: <20200922032651.GA222679@roeck-us.net> (raw)
In-Reply-To: <20200915103806.280265587@infradead.org>
On Tue, Sep 15, 2020 at 12:31:58PM +0200, Peter Zijlstra 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@infradead.org>
> Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> Reported-by: Borislav Petkov <bp@suse.de>
> Tested-by: Borislav Petkov <bp@suse.de>
> ---
> 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)
> {
> }
drivers/acpi/processor_idle.c: In function 'lapic_timer_needs_broadcast':
drivers/acpi/processor_idle.c:179:1: warning: no return statement in function returning non-void [-Wreturn-type]
Should this return true or false ?
Guenter
>
> @@ -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;
next prev parent reply other threads:[~2020-09-22 3:26 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 [this message]
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
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
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20200922032651.GA222679@roeck-us.net \
--to=linux@roeck-us.net \
--cc=bp@alien8.de \
--cc=daniel.lezcano@linaro.org \
--cc=lenb@kernel.org \
--cc=linux-acpi@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-pm@vger.kernel.org \
--cc=naresh.kamboju@linaro.org \
--cc=paulmck@kernel.org \
--cc=peterz@infradead.org \
--cc=rjw@rjwysocki.net \
--cc=tglx@linutronix.de \
--cc=tony.luck@intel.com \
--cc=ulf.hansson@linaro.org \
--cc=x86@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).