On Mon, Jan 23, 2017 at 10:43:10AM +0000, Tvrtko Ursulin wrote: > >@@ -3285,6 +3291,7 @@ int i915_gem_object_set_cache_level(struct drm_i915_gem_object *obj, > > ret = i915_gem_object_wait(obj, > > I915_WAIT_INTERRUPTIBLE | > > I915_WAIT_LOCKED | > >+ I915_WAIT_PRIORITY | > > I915_WAIT_ALL, > > MAX_SCHEDULE_TIMEOUT, > > NULL); > > As mentioned before, is this not a concern? Is it not letting any > userspace boost their prio to max by just calling set cache level > after execbuf? Not any more, set-cache-ioctl now does an explicit unlocked wait first before hitting this wait. Also, the likely cause is though page-flip after execbuf on a fresh bo, which is a stall we don't want. > >--- a/drivers/gpu/drm/i915/intel_ringbuffer.c > >+++ b/drivers/gpu/drm/i915/intel_ringbuffer.c > >@@ -2158,7 +2158,9 @@ static int wait_for_space(struct drm_i915_gem_request *req, int bytes) > > return -ENOSPC; > > > > timeout = i915_wait_request(target, > >- I915_WAIT_INTERRUPTIBLE | I915_WAIT_LOCKED, > >+ I915_WAIT_INTERRUPTIBLE | > >+ I915_WAIT_LOCKED | > >+ I915_WAIT_PRIORITY, > > MAX_SCHEDULE_TIMEOUT); > > This one also look worrying unless I am missing something. Allowing > clients who fill the ring to promote their priority? Yes. They only boost priority for very, very old requests and more importantly these clients are now stalling the entire *system* and not just themselves anymore. So there is an implicit priority inversion through struct_mutex. The only long term solution is avoiding inter-client locks - we still may have inversion on any shared resource, most likely objects, but we can at least reduce the contention by splitting and avoid struct_mutex. -Chris -- Chris Wilson, Intel Open Source Technology Centre _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
