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From: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
To: Chris Wilson <chris@chris-wilson.co.uk>,
	Tvrtko Ursulin <tursulin@ursulin.net>,
	Intel-gfx@lists.freedesktop.org
Subject: Re: [RFC 0/3] Engine utilization tracking
Date: Tue, 9 May 2017 16:16:41 +0100	[thread overview]
Message-ID: <61793260-e1dc-5477-ec95-783f53804d4f@linux.intel.com> (raw)
In-Reply-To: <20170509142640.GE7978@nuc-i3427.alporthouse.com>


On 09/05/2017 15:26, Chris Wilson wrote:
> On Tue, May 09, 2017 at 03:09:33PM +0100, Tvrtko Ursulin wrote:
>> From: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
>>
>> By popular customer demand here is the prototype for cheap engine utilization
>> tracking.
>
> customer and debugfs?

Well I did write in one of the following paragraphs on this topic. 
Perhaps I should have put it in procfs. :) Sysfs API looks restrictive 
or perhaps I missed a way to get low level (fops) access to it.

>> It uses static branches so in the default off case it really should be cheap.
>
> Not as cheap (for the off case) as simply sampling RING_HEAD/RING_TAIL

Off case are three no-op instructions in three places in the irq 
tasklet. And a little bit of object size growth, if you worry about that 
aspect?

> which looks to be the same level of detail. I wrapped all this up in a
> perf interface once up a time...

How does that work? Via periodic sampling? Accuracy sounds like it would 
be proportionate to the sampling frequency, no?

Regards,

Tvrtko
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  reply	other threads:[~2017-05-09 15:16 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-05-09 14:09 [RFC 0/3] Engine utilization tracking Tvrtko Ursulin
2017-05-09 14:09 ` [RFC 1/3] drm/i915: Wrap context schedule notification Tvrtko Ursulin
2017-05-09 14:09 ` [RFC 2/3] drm/i915: Engine busy time tracking Tvrtko Ursulin
2017-05-10 12:41   ` Joonas Lahtinen
2017-05-09 14:09 ` [RFC 3/3] drm/i915: Export engine busy stats in debugfs Tvrtko Ursulin
2017-05-09 18:17   ` Dmitry Rogozhkin
2017-05-10  8:30     ` Tvrtko Ursulin
2017-05-10 15:57       ` Dmitry Rogozhkin
2017-05-09 14:26 ` [RFC 0/3] Engine utilization tracking Chris Wilson
2017-05-09 15:16   ` Tvrtko Ursulin [this message]
2017-05-09 15:29     ` Chris Wilson
2017-05-09 15:51       ` Tvrtko Ursulin
2017-05-09 18:11         ` Dmitry Rogozhkin
2017-05-10  8:38           ` Tvrtko Ursulin
2017-05-10 15:50             ` Dmitry Rogozhkin
2017-05-10 19:45             ` Daniel Vetter
2017-05-12 17:40               ` Dmitry Rogozhkin
2017-05-10 12:31         ` Chris Wilson
2017-05-09 14:51 ` ✓ Fi.CI.BAT: success for " Patchwork

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