[Intel-gfx] [PATCH v7 20/20] drm/i915/vm_bind: Async vm_unbind support

Niranjana Vishwanathapura niranjana.vishwanathapura at intel.com
Tue Nov 15 16:33:47 UTC 2022


On Tue, Nov 15, 2022 at 04:20:54PM +0000, Matthew Auld wrote:
>On 15/11/2022 16:15, Niranjana Vishwanathapura wrote:
>>On Tue, Nov 15, 2022 at 11:05:21AM +0000, Matthew Auld wrote:
>>>On 13/11/2022 07:57, 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.
>>>>
>>>>v2: use i915_vma_destroy_async in vm_unbind ioctl
>>>>
>>>>Signed-off-by: Niranjana Vishwanathapura 
>>>><niranjana.vishwanathapura at intel.com>
>>>
>>>This only does it for non-partial vma, right? Or was that changed 
>>>somewhere?
>>>
>>
>>No, it applies to any vma (partial or non-partial).
>>It was so from the beginning.
>
>Doesn't __i915_vma_unbind_async() return an error when mm.pages != 
>vma->pages? IIRC this was discussed before. Just trying to think about 
>the consequences of this change.

I am not seeing any such restriction. Let me probe and check if there
is any such restriction anywhere in the call chain.

Niranjana

>
>>
>>Niranjana
>>
>>>Reviewed-by: Matthew Auld <matthew.auld at intel.com>
>>>
>>>>---
>>>> .../drm/i915/gem/i915_gem_vm_bind_object.c    |  2 +-
>>>> drivers/gpu/drm/i915/i915_vma.c               | 51 +++++++++++++++++--
>>>> drivers/gpu/drm/i915/i915_vma.h               |  1 +
>>>> include/uapi/drm/i915_drm.h                   |  3 +-
>>>> 4 files changed, 51 insertions(+), 6 deletions(-)
>>>>
>>>>diff --git a/drivers/gpu/drm/i915/gem/i915_gem_vm_bind_object.c 
>>>>b/drivers/gpu/drm/i915/gem/i915_gem_vm_bind_object.c
>>>>index d87d1210365b..36651b447966 100644
>>>>--- a/drivers/gpu/drm/i915/gem/i915_gem_vm_bind_object.c
>>>>+++ b/drivers/gpu/drm/i915/gem/i915_gem_vm_bind_object.c
>>>>@@ -210,7 +210,7 @@ static int i915_gem_vm_unbind_vma(struct 
>>>>i915_address_space *vm,
>>>>      */
>>>>     obj = vma->obj;
>>>>     i915_gem_object_lock(obj, NULL);
>>>>-    i915_vma_destroy(vma);
>>>>+    i915_vma_destroy_async(vma);
>>>>     i915_gem_object_unlock(obj);
>>>>     i915_gem_object_put(obj);
>>>>diff --git a/drivers/gpu/drm/i915/i915_vma.c 
>>>>b/drivers/gpu/drm/i915/i915_vma.c
>>>>index 7cf77c67d755..483d25f2425c 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)
>>>> {
>>>>     /*
>>>>@@ -1713,7 +1715,7 @@ void i915_vma_reopen(struct i915_vma *vma)
>>>>     spin_unlock_irq(&gt->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;
>>>>@@ -1727,7 +1729,21 @@ 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));
>>>> }
>>>>@@ -1787,7 +1803,7 @@ 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);
>>>> }
>>>>@@ -1798,7 +1814,34 @@ 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)
>>>>diff --git a/include/uapi/drm/i915_drm.h b/include/uapi/drm/i915_drm.h
>>>>index e5600f358a15..431d40bb1dee 100644
>>>>--- a/include/uapi/drm/i915_drm.h
>>>>+++ b/include/uapi/drm/i915_drm.h
>>>>@@ -3969,7 +3969,8 @@ struct drm_i915_gem_vm_bind {
>>>>  * any error.
>>>>  *
>>>>  * VM_BIND/UNBIND ioctl calls executed on different CPU threads 
>>>>concurrently
>>>>- * are not ordered.
>>>>+ * are not ordered. Furthermore, parts of the VM_UNBIND 
>>>>operation can be done
>>>>+ * asynchronously.
>>>>  */
>>>> struct drm_i915_gem_vm_unbind {
>>>>     /** @vm_id: VM (address space) id to bind */


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