linux-kernel - Re: [PATCH v3 4/4] /proc/stat: Call kstat_irqs

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Date:   Tue, 15 Jan 2019 10:24:59 +0100 (CET)
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Waiman Long <longman@...hat.com>
cc:     Matthew Wilcox <willy@...radead.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Alexey Dobriyan <adobriyan@...il.com>,
        Kees Cook <keescook@...omium.org>,
        linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        Davidlohr Bueso <dave@...olabs.net>,
        Miklos Szeredi <miklos@...redi.hu>,
        Daniel Colascione <dancol@...gle.com>,
        Dave Chinner <david@...morbit.com>,
        Randy Dunlap <rdunlap@...radead.org>
Subject: Re: [PATCH v3 4/4] /proc/stat: Call kstat_irqs_usr() only for active
 IRQs

Waiman,

On Mon, 14 Jan 2019, Waiman Long wrote:
> On 01/11/2019 04:02 PM, Thomas Gleixner wrote:
> > @@ -919,11 +920,15 @@ unsigned int kstat_irqs_cpu(unsigned int
> >  unsigned int kstat_irqs(unsigned int irq)
> >  {
> >  	struct irq_desc *desc = irq_to_desc(irq);
> > -	int cpu;
> >  	unsigned int sum = 0;
> > +	int cpu;
> >  
> >  	if (!desc || !desc->kstat_irqs)
> >  		return 0;
> > +	if (!irq_settings_is_per_cpu_devid(desc) &&
> > +	    !irq_settings_is_per_cpu(desc))
> > +	    return desc->tot_count;
> > +
> >  	for_each_possible_cpu(cpu)
> >  		sum += *per_cpu_ptr(desc->kstat_irqs, cpu);
> >  	return sum;
> >
> >
> That looks good to me. Thanks for providing a more simple solution.
> 
> BTW, if the percpu IRQ is known at allocation time, maybe we should just
> not allocate a percpu count for the corresponding descriptor.

Nope. You still need the per cpu accounting for /proc/interrupts ...

Thanks,

	tglx