Quoting Lionel Landwerlin (2018-02-21 01:12:46) > On 09/02/18 20:47, Chris Wilson wrote: > > Quoting Daniele Ceraolo Spurio (2018-02-09 18:56:36) > >> > >> On 09/02/18 02:22, Chris Wilson wrote: > >>> Future gen reduce the number of bits we will have available to > >>> differentiate between contexts, so reduce the lifetime of the ID > >>> assignment from that of the context to its current active cycle (i.e. > >>> only while it is pinned for use by the HW, will it have a constant ID). > >>> This means that instead of a max of 2k allocated contexts (worst case > >>> before fun with bit twiddling), we instead have a limit of 2k in flight > >>> contexts (minus a few that have been pinned by the kernel or by perf). > >>> > >> Since we're moving to dynamic assignment would it be reasonable to move > >> the ID to intel_context with an ida per engine class instead of keeping > >> it at the i915_gem_context level? This would allow us to use more > >> contexts as long as they use different classes and it'd take us closer > >> to the way the HW thinks (lrcs on different classes are independent even > >> if they have the same ID). It could also make it easier to use the > >> sw_counter field to expand the maximum number of supported lrcs. > >> Just a thought, we can always do it as a follow up step. > > Certainly doable, leads to lots of refinement about focusing on engines > > rather than global requests (*shivers* every time I think about > > struct_mutex around requests). Afaict, even perf userspace will not care > > if the HW ID vary between engines for the same context; certainly that's > > the only thing that might notice. > > -Chris > > Would it make sense to dedicate part of the HW ID bits to indicate the > engine and the rest a rolling integer that increments each time > something's submitted to the execlist ports?
Hmm. At present, I guess only OA requires a known hw-id. I thought we would need it to service PASID faults (but I guess that isn't really our problem). Can we go completely hw-id less and just using a rolling id? -Chris _______________________________________________ Intel-gfx mailing list Intelemail@example.com https://lists.freedesktop.org/mailman/listinfo/intel-gfx