On 09/08/2019 04:01, Rob Herring wrote: [...] > I was worried too. It seems to be working pretty well though, but more > testing would be good. I don't think there are a lot of usecases that > use more AS than the h/w has (8 on T860), but I'm not sure. Yeah, 8 is overkill. Some GPUs only have 4 which is a little tight and might come to bite when supporting queueing on the GPU. In this patch panfrost_mmu_as_get() will simply WARN() then crash if there isn't a free AS: > WARN_ON(!lru_mmu); > > list_del_init(&lru_mmu->list); > as = lru_mmu->as; This isn't a problem at the moment (there's a maximum of 2 jobs on the GPU at the moment). But when you start queueing jobs it's possible for each job to belong to a different address space. With three slots and for each you can have one job running and one waiting that's a minimum of 6 ASes, plus you might want one configured to dump counters. So a total of 7 are needed to avoid having to wait. Hardware designers like powers of 2 so we have 8. kbase also can be lazy about dealing with completed jobs - this allows even more jobs to be considered "on the GPU" so even with 8 ASes it is possible to "run out"! Steve _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
