Quoting Tvrtko Ursulin (2018-09-17 12:30:55) > From: Lionel Landwerlin <lionel.g.landwerlin@xxxxxxxxx> > > If some of the contexts submitting workloads to the GPU have been > configured to shutdown slices/subslices, we might loose the NOA > configurations written in the NOA muxes. > > One possible solution to this problem is to reprogram the NOA muxes > when we switch to a new context. We initially tried this in the > workaround batchbuffer but some concerns where raised about the cost > of reprogramming at every context switch. This solution is also not > without consequences from the userspace point of view. Reprogramming > of the muxes can only happen once the powergating configuration has > changed (which happens after context switch). This means for a window > of time during the recording, counters recorded by the OA unit might > be invalid. This requires userspace dealing with OA reports to discard > the invalid values. > > Minimizing the reprogramming could be implemented by tracking of the > last programmed configuration somewhere in GGTT and use MI_PREDICATE > to discard some of the programming commands, but the command streamer > would still have to parse all the MI_LRI instructions in the > workaround batchbuffer. > > Another solution, which this change implements, is to simply disregard > the user requested configuration for the period of time when i915/perf > is active. There is no known issue with this apart from a performance > penality for some media workloads that benefit from running on a > partially powergated GPU. We already prevent RC6 from affecting the > programming so it doesn't sound completely unreasonable to hold on > powergating for the same reason. > > v2: Leave RPCS programming in intel_lrc.c (Lionel) > > v3: Update for s/union intel_sseu/struct intel_sseu/ (Lionel) > More to_intel_context() (Tvrtko) > s/dev_priv/i915/ (Tvrtko) > > Tvrtko Ursulin: > > v4: > * Rebase for make_rpcs changes. > > v5: > * Apply OA restriction from make_rpcs directly. > > v6: > * Rebase for context image setup changes. > > v7: > * Move stream assignment before metric enable. > > v8: > * Rebase. > > Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin@xxxxxxxxx> > Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx> Reviewed-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> -Chris _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
