On Tue, Jan 28, 2014 at 09:11:17AM +0100, Daniel Vetter wrote: > On Mon, Jan 27, 2014 at 10:43:07PM +0000, Chris Wilson wrote: > > As the VM do not track activity of objects and instead use a large > > hammer to forcibly idle and evict all of their associated objects when > > one is released, it is possible for that to cause a recursion when we > > need to wait for free space on a ring and call retire requests. > > (intel_ring_begin -> intel_ring_wait_request -> > > i915_gem_retire_requests_ring -> i915_gem_context_free -> > > i915_gem_evict_vm -> i915_gpu_idle -> intel_ring_begin etc) > > Is there no way to get rid of the gpu_idle? Imo doing a gpu idle as part > of the cleanup of a retired request is just not great and has a good > chance to trip us up all over the place since it's _really_ unexpected. Yes, that gpu-idle is only an artifact of lacking activity counting on the vm. > So if we can do it (and iirc we've agreed that all the ppgtt cleanup is > mostly fluff) then I prefer we remove the root-cause instead of just > chopping off another head of the hydra. Look again, I think this is a welcome simplicity to that piece of code. We lose the optimisation of having the most accurate ring->space following the wait in exchange for having a straightforward wait&update. Plus retiring_requests at random points of time has turned out to be a bad idea - wait long enough and I can probably find several other code paths that could explode here. -Chris -- Chris Wilson, Intel Open Source Technology Centre _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/intel-gfx
