linux-kernel - Re: [PATCH 1/1] genirq/cpuhotplug: Bump debugging information print down to KERN

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Message-ID: <YRoXOTRstjKEojuA@google.com>
Date:   Mon, 16 Aug 2021 08:43:53 +0100
From:   Lee Jones <lee.jones@...aro.org>
To:     Thomas Gleixner <tglx@...utronix.de>
Cc:     linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Ming Lei <ming.lei@...hat.com>, Hannes Reinecke <hare@...e.com>
Subject: Re: [PATCH 1/1] genirq/cpuhotplug: Bump debugging information print
 down to KERN_DEBUG

On Wed, 11 Aug 2021, Thomas Gleixner wrote:

> On Wed, Aug 11 2021 at 08:57, Lee Jones wrote:
> > On Tue, 10 Aug 2021, Thomas Gleixner wrote:
> >> > @@ -42,7 +42,7 @@ static inline bool irq_needs_fixup(struct irq_data *d)
> >> >  		 * If this happens then there was a missed IRQ fixup at some
> >> >  		 * point. Warn about it and enforce fixup.
> >> >  		 */
> >> > -		pr_warn("Eff. affinity %*pbl of IRQ %u contains only offline CPUs after offlining CPU %u\n",
> >> 
> >> This one is clearly a warning as this should not happen. See the
> >> comments around that.
> >> 
> >> > +		pr_debug("Eff. affinity %*pbl of IRQ %u contains only offline CPUs after offlining CPU %u\n",
> >> >  			cpumask_pr_args(m), d->irq, cpu);
> >> >  		return true;
> >> >  	}
> >> > @@ -166,7 +166,7 @@ void irq_migrate_all_off_this_cpu(void)
> >> >  		raw_spin_unlock(&desc->lock);
> >> >  
> >> >  		if (affinity_broken) {
> >> > -			pr_warn_ratelimited("IRQ %u: no longer affine to CPU%u\n",
> >> > +			pr_debug_ratelimited("IRQ %u: no longer affine to CPU%u\n",
> >> >  					    irq, smp_processor_id());
> >> 
> >> Maybe, but distro people might have opinions on that.
> >
> > The trouble is, even if these are real warnings, they have an affect
> > on performance on real products.  To the point where so much logging
> > builds up during pre-release testing, that it sets off the watchdog(s)
> > on some high profile consumer devices.
> 
> I'm fine with making the second one debug, but the first one really
> should not trigger at all.

Understood.  I'll follow-up with a subsequent patch and report back
with your advice.  Thanks Thomas.

-- 
Lee Jones [李琼斯]
Senior Technical Lead - Developer Services
Linaro.org │ Open source software for Arm SoCs
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