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From: Frederic Weisbecker <frederic@kernel.org>
To: Mark Rutland <mark.rutland@arm.com>
Cc: linux-arm-kernel@lists.infradead.org, ardb@kernel.org,
	bp@alien8.de, catalin.marinas@arm.com,
	dave.hansen@linux.intel.com, james.morse@arm.com,
	joey.gouly@arm.com, juri.lelli@redhat.com,
	linux-kernel@vger.kernel.org, luto@kernel.org, mingo@redhat.com,
	peterz@infradead.org, tglx@linutronix.de,
	valentin.schneider@arm.com, will@kernel.org
Subject: Re: [PATCH v2 5/7] sched/preempt: add PREEMPT_DYNAMIC using static keys
Date: Mon, 7 Feb 2022 12:57:08 +0100	[thread overview]
Message-ID: <20220207115708.GA514319@lothringen> (raw)
In-Reply-To: <20220204150557.434610-6-mark.rutland@arm.com>

On Fri, Feb 04, 2022 at 03:05:55PM +0000, Mark Rutland wrote:
> diff --git a/include/linux/entry-common.h b/include/linux/entry-common.h
> index dfd84c59b144..141952f4fee8 100644
> --- a/include/linux/entry-common.h
> +++ b/include/linux/entry-common.h
> @@ -456,13 +456,19 @@ irqentry_state_t noinstr irqentry_enter(struct pt_regs *regs);
>   */
>  void raw_irqentry_exit_cond_resched(void);
>  #ifdef CONFIG_PREEMPT_DYNAMIC
> +#if defined(CONFIG_HAVE_PREEMPT_DYNAMIC_CALL)
>  #define irqentry_exit_cond_resched_dynamic_enabled	raw_irqentry_exit_cond_resched
>  #define irqentry_exit_cond_resched_dynamic_disabled	NULL
>  DECLARE_STATIC_CALL(irqentry_exit_cond_resched, raw_irqentry_exit_cond_resched);
>  #define irqentry_exit_cond_resched()	static_call(irqentry_exit_cond_resched)()
> -#else
> -#define irqentry_exit_cond_resched()	raw_irqentry_exit_cond_resched()
> +#elif defined(CONFIG_HAVE_PREEMPT_DYNAMIC_KEY)
> +DECLARE_STATIC_KEY_TRUE(sk_dynamic_irqentry_exit_cond_resched);

If CONFIG_PREEMPT && CONFIG_PREEMPT_DYNAMIC and no "preempt=" parameter is
passed, nothing is overriden on boot. So you need to either have cond_resched
and might_resched initially disabled (STATIC_KEY_FALSE?) or call
sched_dynamic_update() from preempt_dynamic_init() also when CONFIG_PREEMPT=y.

Thanks.

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http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

WARNING: multiple messages have this Message-ID (diff)
From: Frederic Weisbecker <frederic@kernel.org>
To: Mark Rutland <mark.rutland@arm.com>
Cc: linux-arm-kernel@lists.infradead.org, ardb@kernel.org,
	bp@alien8.de, catalin.marinas@arm.com,
	dave.hansen@linux.intel.com, james.morse@arm.com,
	joey.gouly@arm.com, juri.lelli@redhat.com,
	linux-kernel@vger.kernel.org, luto@kernel.org, mingo@redhat.com,
	peterz@infradead.org, tglx@linutronix.de,
	valentin.schneider@arm.com, will@kernel.org
Subject: Re: [PATCH v2 5/7] sched/preempt: add PREEMPT_DYNAMIC using static keys
Date: Mon, 7 Feb 2022 12:57:08 +0100	[thread overview]
Message-ID: <20220207115708.GA514319@lothringen> (raw)
In-Reply-To: <20220204150557.434610-6-mark.rutland@arm.com>

On Fri, Feb 04, 2022 at 03:05:55PM +0000, Mark Rutland wrote:
> diff --git a/include/linux/entry-common.h b/include/linux/entry-common.h
> index dfd84c59b144..141952f4fee8 100644
> --- a/include/linux/entry-common.h
> +++ b/include/linux/entry-common.h
> @@ -456,13 +456,19 @@ irqentry_state_t noinstr irqentry_enter(struct pt_regs *regs);
>   */
>  void raw_irqentry_exit_cond_resched(void);
>  #ifdef CONFIG_PREEMPT_DYNAMIC
> +#if defined(CONFIG_HAVE_PREEMPT_DYNAMIC_CALL)
>  #define irqentry_exit_cond_resched_dynamic_enabled	raw_irqentry_exit_cond_resched
>  #define irqentry_exit_cond_resched_dynamic_disabled	NULL
>  DECLARE_STATIC_CALL(irqentry_exit_cond_resched, raw_irqentry_exit_cond_resched);
>  #define irqentry_exit_cond_resched()	static_call(irqentry_exit_cond_resched)()
> -#else
> -#define irqentry_exit_cond_resched()	raw_irqentry_exit_cond_resched()
> +#elif defined(CONFIG_HAVE_PREEMPT_DYNAMIC_KEY)
> +DECLARE_STATIC_KEY_TRUE(sk_dynamic_irqentry_exit_cond_resched);

If CONFIG_PREEMPT && CONFIG_PREEMPT_DYNAMIC and no "preempt=" parameter is
passed, nothing is overriden on boot. So you need to either have cond_resched
and might_resched initially disabled (STATIC_KEY_FALSE?) or call
sched_dynamic_update() from preempt_dynamic_init() also when CONFIG_PREEMPT=y.

Thanks.

  reply	other threads:[~2022-02-07 11:58 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-02-04 15:05 [PATCH v2 0/7] arm64 / sched/preempt: support PREEMPT_DYNAMIC with static keys Mark Rutland
2022-02-04 15:05 ` Mark Rutland
2022-02-04 15:05 ` [PATCH v2 1/7] sched/preempt: move PREEMPT_DYNAMIC logic later Mark Rutland
2022-02-04 15:05   ` Mark Rutland
2022-02-04 15:05 ` [PATCH v2 2/7] sched/preempt: refactor sched_dynamic_update() Mark Rutland
2022-02-04 15:05   ` Mark Rutland
2022-02-04 15:05 ` [PATCH v2 3/7] sched/preempt: simplify irqentry_exit_cond_resched() callers Mark Rutland
2022-02-04 15:05   ` Mark Rutland
2022-02-04 15:05 ` [PATCH v2 4/7] sched/preempt: decouple HAVE_PREEMPT_DYNAMIC from GENERIC_ENTRY Mark Rutland
2022-02-04 15:05   ` Mark Rutland
2022-02-04 15:05 ` [PATCH v2 5/7] sched/preempt: add PREEMPT_DYNAMIC using static keys Mark Rutland
2022-02-04 15:05   ` Mark Rutland
2022-02-07 11:57   ` Frederic Weisbecker [this message]
2022-02-07 11:57     ` Frederic Weisbecker
2022-02-08 12:15     ` Mark Rutland
2022-02-08 12:15       ` Mark Rutland
2022-02-04 15:05 ` [PATCH v2 6/7] arm64: entry: centralize premeption decision Mark Rutland
2022-02-04 15:05   ` Mark Rutland
2022-02-04 18:46   ` Catalin Marinas
2022-02-04 18:46     ` Catalin Marinas
2022-02-04 15:05 ` [PATCH v2 7/7] arm64: support PREEMPT_DYNAMIC Mark Rutland
2022-02-04 15:05   ` Mark Rutland
2022-02-04 18:48   ` Catalin Marinas
2022-02-04 18:48     ` Catalin Marinas
2022-02-04 20:41   ` kernel test robot

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