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.ursu...@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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