linux-kernel - Re: [PATCH 3/3] time: drop local_irq_save/restore from irqtime_account

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Message-ID: <fe747bb3-03ff-2056-e088-f9499dfc76b8@redhat.com>
Date:	Mon, 11 Jul 2016 19:03:39 +0200
From:	Paolo Bonzini <pbonzini@...hat.com>
To:	riel@...hat.com, linux-kernel@...r.kernel.org
Cc:	peterz@...radead.org, mingo@...nel.org, fweisbec@...hat.com,
	wanpeng.li@...mail.com, efault@....de, tglx@...utronix.de,
	rkrcmar@...hat.com
Subject: Re: [PATCH 3/3] time: drop local_irq_save/restore from
 irqtime_account_irq



On 11/07/2016 18:53, riel@...hat.com wrote:
> From: Rik van Riel <riel@...hat.com>
> 
> Paolo pointed out that irqs are already blocked when irqtime_account_irq
> is called. That means there is no reason to call local_irq_save/restore
> again.
> 
> Signed-off-by: Rik van Riel <riel@...hat.com>
> Suggested-by: Paolo Bonzini <pbonzini@...hat.com>
> ---
>  kernel/sched/cputime.c | 4 ----
>  1 file changed, 4 deletions(-)
> 
> diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c
> index ca7e33cb0967..7b6fa4d7ad4c 100644
> --- a/kernel/sched/cputime.c
> +++ b/kernel/sched/cputime.c
> @@ -49,15 +49,12 @@ DEFINE_PER_CPU(seqcount_t, irq_time_seq);
>   */
>  void irqtime_account_irq(struct task_struct *curr)
>  {
> -	unsigned long flags;
>  	s64 delta;
>  	int cpu;
>  
>  	if (!sched_clock_irqtime)
>  		return;
>  
> -	local_irq_save(flags);
> -
>  	cpu = smp_processor_id();
>  	delta = sched_clock_cpu(cpu) - __this_cpu_read(irq_start_time);
>  	__this_cpu_add(irq_start_time, delta);
> @@ -75,7 +72,6 @@ void irqtime_account_irq(struct task_struct *curr)
>  		__this_cpu_add(cpu_softirq_time, delta);
>  
>  	irq_time_write_end();
> -	local_irq_restore(flags);
>  }
>  EXPORT_SYMBOL_GPL(irqtime_account_irq);
>  
> 

Reviewed-by: Paolo Bonzini <pbonzini@...hat.com>