Quoting Tvrtko Ursulin (2019-09-23 09:10:26) > > On 20/09/2019 17:35, Chris Wilson wrote: > > Quoting Tvrtko Ursulin (2019-09-20 17:22:42) > >> > >> On 02/09/2019 05:02, Chris Wilson wrote: > >>> Since we cannot allocate underneath the vm->mutex (it is used in the > >>> direct-reclaim paths), we need to shift the allocations off into a > >>> mutexless worker with fence recursion prevention. To know when we need > >>> this protection, we mark up the address spaces that do allocate before > >>> insertion. > >>> > >>> Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> > >>> --- > >>> drivers/gpu/drm/i915/i915_gem_gtt.c | 3 +++ > >>> drivers/gpu/drm/i915/i915_gem_gtt.h | 2 ++ > >>> 2 files changed, 5 insertions(+) > >>> > >>> diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c > >>> index 9095f017162e..56d27cf09a3d 100644 > >>> --- a/drivers/gpu/drm/i915/i915_gem_gtt.c > >>> +++ b/drivers/gpu/drm/i915/i915_gem_gtt.c > >>> @@ -1500,6 +1500,7 @@ static struct i915_ppgtt *gen8_ppgtt_create(struct drm_i915_private *i915) > >>> goto err_free_pd; > >>> } > >>> > >>> + ppgtt->vm.bind_alloc = I915_VMA_LOCAL_BIND; > >> > >> So this is re-using I915_VMA_LOCAL_BIND as a trick? Is it clear how that > >> works from these call sites? Should it be called bind_alloc*s*? > >> bind_allocates? Or be a boolean which is converted to a trick flag in > >> i915_vma_bind where a comment can be put explaining the trick? > > > > Is it a trick? We need to differentiate between requests for LOCAL_BIND, > > GLOBAL_BIND, LOCAL_BIND | GLOBAL_BIND, for different types of vm. Then I > > have a plan on using the worker for GLOBAL_BIND on bsw/bxt to defer the > > stop_machine(). > > What's the connection between "mark up the address spaces that do > allocate before insertion" and I915_VMA_LOCAL_BIND? Full-ppgtt is only accessible by PIN_USER. Aliasing-ppgtt is accessible from global-gtt as PIN_USER. Only if we have an aliasing-gtt behind ggtt do we want to allocate for ggtt for local binds. global-gtt by itself never allocates and is expected to be synchronous. However, we do use stop_machine() for bxt/bsw and that unfortunately is marked as an allocating mutex so one idea I had for avoiding that lockdep splat was to make bxt/bsw PIN_GLOBAL async. -Chris _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
