Quoting Tvrtko Ursulin (2020-07-17 09:34:07) > > On 16/07/2020 21:44, Chris Wilson wrote: > I am not sure if the batch duration is not too short in practice, the > add loop will really rapidly end all, just needs 64 iterations on > average to end all 32 I think. So 64 WC writes from the CPU compared to > CSB processing and breadcrumb signaling latencies might be too short. > Maybe some small random udelays in the loop would be more realistic. > Maybe as a 2nd flavour of the test just in case.. more coverage the better. GPU kernel IGT semaphore wait -> raise interrupt handle interrupt -> kick tasklet begin preempt-to-busy semaphore signal semaphore completes request completes submit new ELSP[] -> stale unwound request Duration of the batch/semaphore itself doesn't really factor into it, it's that we have to let batch complete after we begin the process of scheduling it out for an expired timeslice. It's such a small window and I don't see a good way of hitting it reliably from userspace. With some printk, I was able to confirm that we were timeslicing virtual requests and moving them between engines with active breadcrumbs. But I never once saw any of the bugs with the stale requests, using this test. Somehow we want to length the preempt-to-busy window and coincide the request completion at the same time. So far all I have is yucky (too single purpose, we would be better off writing unit tests for each of the steps involved). -Chris _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
