Quoting Tvrtko Ursulin (2019-01-08 13:22:48) > 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. Lets squash patch 6 here and update the commit message/comments to reflect. With that done, the resulting patch is: Reviewed-by: Joonas Lahtinen <joonas.lahtinen@xxxxxxxxxxxxxxx> Regards, Joonas _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
