On 03/30/2019 03:14 AM, Chris Wilson wrote: > Quoting Xiaolin Zhang (2019-03-29 13:32:40) >> + spin_lock(&engine->i915->vgpu.shared_page_lock); >> + shared_page->ring_id = engine->id; >> + for (n = 0; n < execlists_num_ports(execlists); n++) >> + shared_page->descs[n] = descs[n]; >> + >> + __raw_i915_write32(uncore, vgtif_reg(g2v_notify), >> + VGT_G2V_PV_SUBMISSION); > There's no serialisation with the consumer here. The > shared_page->descs[] will be clobbered by a second engine before they > are read by pv. There should be a wait-for-ack here, or separate > channels for each engine. In execlists, we avoid this by not dequeuing > until after we get a response/ack from HW. > > Preemption? I guess preemption was turned off, or else you have to worry > about the same engine overwriting the desc[] (if no ack). > -Chris > Chris, thanks you to point it out my flaw here. will use the per-engine channel for notification. preemption is turned off and no support in current version. _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
