[Intel-gfx] [PATCH v6 3/3] drm/i915: Predictive governor to control slice/subslice/eu

[Chris Wilson]

Quoting Tvrtko Ursulin (2019-11-26 10:51:22)
> You mentioned you did some experiment where you did something on context 
> pinning and that it did not work so well. I don't know what that was 
> though. I don't think that was ever posted?
> 
> What I am thinking is this: You drop the timer altogether. Instead in 
> __execlists_update_reg_state you look at your gem_context->req_cnt and 
> implement your logic there.

I noticed the same non-sequitur. Except I would push that either the
entire measurement and hence patch series is bogus (beyond the patches
themselves being trivially broken, tested much?), or that it really
should be done from a timer and also adjust pinned contexts ala
reconfigure_sseu.

A bunch of selftests and igt proving that different sseu setups do
consume different power (i.e. that we can adjust sseu correctly),
along with demonstrating good workloads where autotuning produces
beneficial results is a must.

Also given Tvrtko's stats, this could all be done from userspace with an
extended CONTEXT_PARAM_SSEU, so why would we not do it that way?
-Chris