On Mon, 2022-11-07 at 00:52 -0800, Niranjana Vishwanathapura wrote:
> Asynchronously unbind the vma upon vm_unbind call.
> Fall back to synchronous unbind if backend doesn't support
> async unbind or if async unbind fails.
>
> No need for vm_unbind out fence support as i915 will internally
> handle all sequencing and user need not try to sequence any
> operation with the unbind completion.
Can you please provide some more details on how this works from the
user space point of view? I want to be able to know with 100% certainty
if an unbind has already happened, so I can reuse that vma or whatever
else I may decide to do. I see the interface does not provide any sort
of drm_syncobjs for me to wait on the async unbind. So, when does the
unbind really happen? When can I be sure it's past so I can do stuff
with it? Why would you provide an async ioctl and provide no means for
user space to wait on it?
Thanks,
Paulo
>
> Signed-off-by: Niranjana Vishwanathapura <niranjana.vishwanathapura@xxxxxxxxx>
> ---
> drivers/gpu/drm/i915/i915_vma.c | 51 ++++++++++++++++++++++++++++++---
> drivers/gpu/drm/i915/i915_vma.h | 1 +
> 2 files changed, 48 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_vma.c b/drivers/gpu/drm/i915/i915_vma.c
> index 08218e3a2f12..03c966fad87b 100644
> --- a/drivers/gpu/drm/i915/i915_vma.c
> +++ b/drivers/gpu/drm/i915/i915_vma.c
> @@ -42,6 +42,8 @@
> #include "i915_vma.h"
> #include "i915_vma_resource.h"
>
>
>
>
> +static struct dma_fence *__i915_vma_unbind_async(struct i915_vma *vma);
> +
> static inline void assert_vma_held_evict(const struct i915_vma *vma)
> {
> /*
> @@ -1711,7 +1713,7 @@ void i915_vma_reopen(struct i915_vma *vma)
> spin_unlock_irq(>->closed_lock);
> }
>
>
>
>
> -static void force_unbind(struct i915_vma *vma)
> +static void force_unbind(struct i915_vma *vma, bool async)
> {
> if (!drm_mm_node_allocated(&vma->node))
> return;
> @@ -1725,7 +1727,21 @@ static void force_unbind(struct i915_vma *vma)
> i915_vma_set_purged(vma);
>
>
>
>
> atomic_and(~I915_VMA_PIN_MASK, &vma->flags);
> - WARN_ON(__i915_vma_unbind(vma));
> + if (async) {
> + struct dma_fence *fence;
> +
> + fence = __i915_vma_unbind_async(vma);
> + if (IS_ERR_OR_NULL(fence)) {
> + async = false;
> + } else {
> + dma_resv_add_fence(vma->obj->base.resv, fence,
> + DMA_RESV_USAGE_READ);
> + dma_fence_put(fence);
> + }
> + }
> +
> + if (!async)
> + WARN_ON(__i915_vma_unbind(vma));
> GEM_BUG_ON(drm_mm_node_allocated(&vma->node));
> }
>
>
>
>
> @@ -1785,7 +1801,7 @@ void i915_vma_destroy_locked(struct i915_vma *vma)
> {
> lockdep_assert_held(&vma->vm->mutex);
>
>
>
>
> - force_unbind(vma);
> + force_unbind(vma, false);
> list_del_init(&vma->vm_link);
> release_references(vma, vma->vm->gt, false);
> }
> @@ -1796,7 +1812,34 @@ void i915_vma_destroy(struct i915_vma *vma)
> bool vm_ddestroy;
>
>
>
>
> mutex_lock(&vma->vm->mutex);
> - force_unbind(vma);
> + force_unbind(vma, false);
> + list_del_init(&vma->vm_link);
> + vm_ddestroy = vma->vm_ddestroy;
> + vma->vm_ddestroy = false;
> +
> + /* vma->vm may be freed when releasing vma->vm->mutex. */
> + gt = vma->vm->gt;
> + mutex_unlock(&vma->vm->mutex);
> + release_references(vma, gt, vm_ddestroy);
> +}
> +
> +void i915_vma_destroy_async(struct i915_vma *vma)
> +{
> + bool vm_ddestroy, async = vma->obj->mm.rsgt;
> + struct intel_gt *gt;
> +
> + if (dma_resv_reserve_fences(vma->obj->base.resv, 1))
> + async = false;
> +
> + mutex_lock(&vma->vm->mutex);
> + /*
> + * Ensure any asynchronous binding is complete while using
> + * async unbind as we will be releasing the vma here.
> + */
> + if (async && i915_active_wait(&vma->active))
> + async = false;
> +
> + force_unbind(vma, async);
> list_del_init(&vma->vm_link);
> vm_ddestroy = vma->vm_ddestroy;
> vma->vm_ddestroy = false;
> diff --git a/drivers/gpu/drm/i915/i915_vma.h b/drivers/gpu/drm/i915/i915_vma.h
> index 737ef310d046..25f15965dab8 100644
> --- a/drivers/gpu/drm/i915/i915_vma.h
> +++ b/drivers/gpu/drm/i915/i915_vma.h
> @@ -272,6 +272,7 @@ void i915_vma_reopen(struct i915_vma *vma);
>
>
>
>
> void i915_vma_destroy_locked(struct i915_vma *vma);
> void i915_vma_destroy(struct i915_vma *vma);
> +void i915_vma_destroy_async(struct i915_vma *vma);
>
>
>
>
> #define assert_vma_held(vma) dma_resv_assert_held((vma)->obj->base.resv)
>
>
>
>
