linux-kernel - Re: [Intel-gfx] [PATCH v3 2/4] drm/i915/pmu: Use kstat

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Message-ID: <118a2e24-12f8-8a5c-193e-67e5ac37cac1@linux.intel.com>
Date:   Thu, 10 Dec 2020 17:51:07 +0000
From:   Tvrtko Ursulin <tvrtko.ursulin@...ux.intel.com>
To:     Thomas Gleixner <tglx@...utronix.de>,
        Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>,
        Jerry Snitselaar <jsnitsel@...hat.com>,
        linux-kernel@...r.kernel.org,
        Tvrtko Ursulin <tvrtko.ursulin@...el.com>,
        Chris Wilson <chris@...is-wilson.co.uk>
Cc:     Jason Gunthorpe <jgg@...pe.ca>,
        Peter Zijlstra <peterz@...radead.org>,
        intel-gfx@...ts.freedesktop.org,
        Matthew Garrett <mjg59@...gle.com>,
        James Bottomley <James.Bottomley@...senPartnership.com>,
        David Airlie <airlied@...ux.ie>,
        Jarkko Sakkinen <jarkko@...nel.org>,
        dri-devel@...ts.freedesktop.org, linux-integrity@...r.kernel.org,
        Peter Huewe <peterhuewe@....de>
Subject: Re: [Intel-gfx] [PATCH v3 2/4] drm/i915/pmu: Use kstat_irqs to get
 interrupt count


On 10/12/2020 17:44, Thomas Gleixner wrote:
> On Thu, Dec 10 2020 at 17:09, Tvrtko Ursulin wrote:
>> On 10/12/2020 16:35, Thomas Gleixner wrote:
>>> I'll send out a series addressing irq_to_desc() (ab)use all over the
>>> place shortly. i915 is in there...
>>
>> Yep we don't need atomic, my bad. And we would care about the shared
>> interrupt line. And without atomic the extra accounting falls way below
>> noise.
> 
> You have to be careful though. If you make the accumulated counter 64
> bit wide then you need to be careful vs. 32bit machines.

Yep, thanks, I am bad jumping from one thing to another. Forgot about 
the read side atomicity completely..

>> So in the light of it all, it sounds best I just quickly replace our
>> abuse with private counting and then you don't have to deal with it in
>> your series.
> 
> I mostly have it. Still chewing on the 32bit vs. 64bit thing. And
> keeping it in my series allows me to remove the export of irq_to_desc()
> at the end without waiting for your tree to be merged.
> 
> Give me a few.

Ok.

Regards,

Tvrtko