linux-kernel - Re: [PATCH 5/7] thermal: intel: hfi: Enable notification interrupt

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Date:   Tue, 9 Nov 2021 07:00:01 -0800
From:   Ricardo Neri <ricardo.neri-calderon@...ux.intel.com>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        linux-pm@...r.kernel.org, x86@...nel.org,
        linux-doc@...r.kernel.org, Len Brown <len.brown@...el.com>,
        Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>,
        Aubrey Li <aubrey.li@...ux.intel.com>,
        Amit Kucheria <amitk@...nel.org>,
        Andi Kleen <ak@...ux.intel.com>,
        Tim Chen <tim.c.chen@...ux.intel.com>,
        "Ravi V. Shankar" <ravi.v.shankar@...el.com>,
        Ricardo Neri <ricardo.neri@...el.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 5/7] thermal: intel: hfi: Enable notification interrupt

On Mon, Nov 08, 2021 at 10:01:04AM +0100, Peter Zijlstra wrote:
> On Fri, Nov 05, 2021 at 06:33:10PM -0700, Ricardo Neri wrote:
> > +	/*
> > +	 * On most systems, all CPUs in the package receive a package-level
> > +	 * thermal interrupt when there is an HFI update. Since they all are
> > +	 * dealing with the same update (as indicated by the update timestamp),
> > +	 * it is sufficient to let a single CPU to acknowledge the update and
> > +	 * schedule work to process it.
> > +	 */
> 
> That's pretty crap hardware behaviour. Is there really no way to steer
> these interrupts?

The HFI is a package-level thermal interrupt. Hence, all CPUs get it.
AFAIK there is no way to steer the interrupts.

Thanks and BR,
Ricardo