Re: [Intel-gfx] [PATCH 05/20] drm/i915/gem: Break apart the early i915_vma_pin from execbuf object lookup

[Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>]

On 06/07/2020 07:19, Chris Wilson wrote:
> As a prelude to the next step where we want to perform all the object
> allocations together under the same lock, we first must delay the
> i915_vma_pin() as that implicitly does the allocations for us, one by
> one. As it only does the allocations one by one, it is not allowed to
> wait/evict, whereas pulling all the allocations together the entire set
> can be scheduled as one.
> 
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> ---
>   .../gpu/drm/i915/gem/i915_gem_execbuffer.c    | 70 +++++++++++--------
>   1 file changed, 39 insertions(+), 31 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
> index bf8193d9e279..35a57c1fc9c3 100644
> --- a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
> +++ b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
> @@ -33,6 +33,8 @@ struct eb_vma {
>   
>   	/** This vma's place in the execbuf reservation list */
>   	struct drm_i915_gem_exec_object2 *exec;
> +
> +	struct list_head bind_link;
>   	struct list_head unbound_link;
>   	struct list_head reloc_link;
>   
> @@ -240,8 +242,8 @@ struct i915_execbuffer {
>   	/** actual size of execobj[] as we may extend it for the cmdparser */
>   	unsigned int buffer_count;
>   
> -	/** list of vma not yet bound during reservation phase */
> -	struct list_head unbound;
> +	/** list of all vma required to bound for this execbuf */
> +	struct list_head bind_list;
>   
>   	/** list of vma that have execobj.relocation_count */
>   	struct list_head relocs;
> @@ -565,6 +567,8 @@ eb_add_vma(struct i915_execbuffer *eb,
>   						    eb->lut_size)]);
>   	}
>   
> +	list_add_tail(&ev->bind_link, &eb->bind_list);
> +
>   	if (entry->relocation_count)
>   		list_add_tail(&ev->reloc_link, &eb->relocs);
>   
> @@ -586,16 +590,6 @@ eb_add_vma(struct i915_execbuffer *eb,
>   
>   		eb->batch = ev;
>   	}
> -
> -	if (eb_pin_vma(eb, entry, ev)) {
> -		if (entry->offset != vma->node.start) {
> -			entry->offset = vma->node.start | UPDATE;
> -			eb->args->flags |= __EXEC_HAS_RELOC;
> -		}
> -	} else {
> -		eb_unreserve_vma(ev);
> -		list_add_tail(&ev->unbound_link, &eb->unbound);
> -	}
>   }
>   
>   static int eb_reserve_vma(const struct i915_execbuffer *eb,
> @@ -670,13 +664,31 @@ static int wait_for_timeline(struct intel_timeline *tl)
>   	} while (1);
>   }
>   
> -static int eb_reserve(struct i915_execbuffer *eb)
> +static int eb_reserve_vm(struct i915_execbuffer *eb)
>   {
> -	const unsigned int count = eb->buffer_count;
>   	unsigned int pin_flags = PIN_USER | PIN_NONBLOCK;
> -	struct list_head last;
> +	struct list_head last, unbound;
>   	struct eb_vma *ev;
> -	unsigned int i, pass;
> +	unsigned int pass;
> +
> +	INIT_LIST_HEAD(&unbound);
> +	list_for_each_entry(ev, &eb->bind_list, bind_link) {
> +		struct drm_i915_gem_exec_object2 *entry = ev->exec;
> +		struct i915_vma *vma = ev->vma;
> +
> +		if (eb_pin_vma(eb, entry, ev)) {
> +			if (entry->offset != vma->node.start) {
> +				entry->offset = vma->node.start | UPDATE;
> +				eb->args->flags |= __EXEC_HAS_RELOC;
> +			}
> +		} else {
> +			eb_unreserve_vma(ev);
> +			list_add_tail(&ev->unbound_link, &unbound);
> +		}
> +	}
> +
> +	if (list_empty(&unbound))
> +		return 0;
>   
>   	/*
>   	 * Attempt to pin all of the buffers into the GTT.
> @@ -699,7 +711,7 @@ static int eb_reserve(struct i915_execbuffer *eb)
>   		if (mutex_lock_interruptible(&eb->i915->drm.struct_mutex))
>   			return -EINTR;
>   
> -		list_for_each_entry(ev, &eb->unbound, unbound_link) {
> +		list_for_each_entry(ev, &unbound, unbound_link) {
>   			err = eb_reserve_vma(eb, ev, pin_flags);
>   			if (err)
>   				break;
> @@ -710,13 +722,11 @@ static int eb_reserve(struct i915_execbuffer *eb)
>   		}
>   
>   		/* Resort *all* the objects into priority order */
> -		INIT_LIST_HEAD(&eb->unbound);
> +		INIT_LIST_HEAD(&unbound);
>   		INIT_LIST_HEAD(&last);
> -		for (i = 0; i < count; i++) {
> -			unsigned int flags;
> +		list_for_each_entry(ev, &eb->bind_list, bind_link) {
> +			unsigned int flags = ev->flags;
>   
> -			ev = &eb->vma[i];
> -			flags = ev->flags;
>   			if (flags & EXEC_OBJECT_PINNED &&
>   			    flags & __EXEC_OBJECT_HAS_PIN)
>   				continue;
> @@ -725,17 +735,17 @@ static int eb_reserve(struct i915_execbuffer *eb)
>   
>   			if (flags & EXEC_OBJECT_PINNED)
>   				/* Pinned must have their slot */
> -				list_add(&ev->unbound_link, &eb->unbound);
> +				list_add(&ev->unbound_link, &unbound);
>   			else if (flags & __EXEC_OBJECT_NEEDS_MAP)
>   				/* Map require the lowest 256MiB (aperture) */
> -				list_add_tail(&ev->unbound_link, &eb->unbound);
> +				list_add_tail(&ev->unbound_link, &unbound);
>   			else if (!(flags & EXEC_OBJECT_SUPPORTS_48B_ADDRESS))
>   				/* Prioritise 4GiB region for restricted bo */
>   				list_add(&ev->unbound_link, &last);
>   			else
>   				list_add_tail(&ev->unbound_link, &last);
>   		}
> -		list_splice_tail(&last, &eb->unbound);
> +		list_splice_tail(&last, &unbound);
>   		mutex_unlock(&eb->i915->drm.struct_mutex);
>   
>   		if (err == -EAGAIN) {
> @@ -891,8 +901,8 @@ static int eb_lookup_vmas(struct i915_execbuffer *eb)
>   	unsigned int i;
>   	int err = 0;
>   
> +	INIT_LIST_HEAD(&eb->bind_list);
>   	INIT_LIST_HEAD(&eb->relocs);
> -	INIT_LIST_HEAD(&eb->unbound);
>   
>   	for (i = 0; i < eb->buffer_count; i++) {
>   		struct i915_vma *vma;
> @@ -1539,11 +1549,9 @@ static int eb_relocate(struct i915_execbuffer *eb)
>   	if (err)
>   		return err;
>   
> -	if (!list_empty(&eb->unbound)) {
> -		err = eb_reserve(eb);
> -		if (err)
> -			return err;
> -	}
> +	err = eb_reserve_vm(eb);
> +	if (err)
> +		return err;
>   
>   	/* The objects are in their final locations, apply the relocations. */
>   	if (eb->args->flags & __EXEC_HAS_RELOC) {
> 

Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>

Regards,

Tvrtko
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