[Intel-gfx] [RFC 00/12] Per client engine busyness

[Chris Wilson]

Quoting Tvrtko Ursulin (2020-03-09 18:31:17)
> From: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
> 
> Another re-spin of the per-client engine busyness series. Highlights from this
> version:
> 
>  * Different way of tracking runtime of exited/unreachable context. This time
>    round I accumulate those per context/client and engine class, but active
>    contexts are kept in a list and tallied on sysfs reads.
>  * I had to do a small tweak in the engine release code since I needed the
>    GEM context for a bit longer. (So I can accumulate the intel_context runtime
>    into it as it is getting freed, because context complete can be late.)
>  * PPHWSP method is back and even comes first in the series this time. It still
>    can't show the currently running workloads but the software tracking method
>    suffers from the CSB processing delay with high frequency and very short
>    batches.

I bet it's ksoftirqd, but this could be quite problematic for us.
gem_exec_nop/foo? I wonder if this also ties into how much harder it is
to saturate the GPU with nops from userspace than it is from the kernel.
-Chris