linux-kernel - Re: [PATCH v7 2/6] sched: Add helper kstat_cpu_softirqs

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Message-ID: <20221114114252.GA590078@lothringen>
Date:   Mon, 14 Nov 2022 12:42:52 +0100
From:   Frederic Weisbecker <frederic@...nel.org>
To:     Zhen Lei <thunder.leizhen@...wei.com>
Cc:     "Paul E . McKenney" <paulmck@...nel.org>,
        Neeraj Upadhyay <quic_neeraju@...cinc.com>,
        Josh Triplett <josh@...htriplett.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
        Lai Jiangshan <jiangshanlai@...il.com>,
        Joel Fernandes <joel@...lfernandes.org>, rcu@...r.kernel.org,
        linux-kernel@...r.kernel.org, Robert Elliott <elliott@....com>
Subject: Re: [PATCH v7 2/6] sched: Add helper kstat_cpu_softirqs_sum()

On Fri, Nov 11, 2022 at 09:07:05PM +0800, Zhen Lei wrote:
> Similar to kstat_cpu_irqs_sum(), it counts the sum of all software
> interrupts on a specified CPU.
> 
> Signed-off-by: Zhen Lei <thunder.leizhen@...wei.com>
> ---
>  include/linux/kernel_stat.h | 11 +++++++++++
>  1 file changed, 11 insertions(+)
> 
> diff --git a/include/linux/kernel_stat.h b/include/linux/kernel_stat.h
> index 90e2fdc17d79ff8..898076e173a928a 100644
> --- a/include/linux/kernel_stat.h
> +++ b/include/linux/kernel_stat.h
> @@ -67,6 +67,17 @@ static inline unsigned int kstat_softirqs_cpu(unsigned int irq, int cpu)
>         return kstat_cpu(cpu).softirqs[irq];
>  }
>  
> +static inline unsigned int kstat_cpu_softirqs_sum(int cpu)
> +{
> +	int i;
> +	unsigned int sum = 0;
> +
> +	for (i = 0; i < NR_SOFTIRQS; i++)
> +		sum += kstat_softirqs_cpu(i, cpu);

This should return a u64 or at least an unsigned long so that high
numbers of CPUs don't overflow easily.

Thanks.

> +
> +	return sum;
> +}
> +
>  /*
>   * Number of interrupts per specific IRQ source, since bootup
>   */
> -- 
> 2.25.1
>