[Intel-gfx] [PATCH 07/53] drm/i915: Early alloc request in execbuff

[Tomas Elf]

On 19/02/2015 17:17, John.C.Harrison at Intel.com wrote:
> From: John Harrison <John.C.Harrison at Intel.com>
>
> Start of explicit request management in the execbuffer code path. This patch
> adds a call to allocate a request structure before all the actual hardware work
> is done. Thus guaranteeing that all that work is tagged by a known request. At
> present, nothing further is done with the request, the rest comes later in the
> series.
>
> The only noticable change is that failure to get a request (e.g. due to lack of
> memory) will be caught earlier in the sequence. It now occurs right at the start
> before any un-undoable work has been done.
>
> For: VIZ-5115
> Signed-off-by: John Harrison <John.C.Harrison at Intel.com>
> ---
>   drivers/gpu/drm/i915/i915_gem_execbuffer.c |   13 ++++++++++---
>   1 file changed, 10 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
> index ca85803..61471e9 100644
> --- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c
> +++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
> @@ -1356,7 +1356,7 @@ i915_gem_do_execbuffer(struct drm_device *dev, void *data,
>   	const u32 ctx_id = i915_execbuffer2_get_context_id(*args);
>   	u32 dispatch_flags;
>   	int ret;
> -	bool need_relocs;
> +	bool need_relocs, batch_pinned = false;
>
>   	if (!i915_gem_check_execbuffer(args))
>   		return -EINVAL;
> @@ -1525,10 +1525,16 @@ i915_gem_do_execbuffer(struct drm_device *dev, void *data,
>   		if (ret)
>   			goto err;
>
> +		batch_pinned = true;
>   		params->batch_obj_vm_offset = i915_gem_obj_ggtt_offset(batch_obj);
>   	} else
>   		params->batch_obj_vm_offset = i915_gem_obj_offset(batch_obj, vm);
>
> +	/* Allocate a request for this batch buffer nice and early. */
> +	ret = dev_priv->gt.alloc_request(ring, ctx);
> +	if (ret)
> +		goto err;
> +
>   	/*
>   	 * Save assorted stuff away to pass through to *_submission().
>   	 * NB: This data should be 'persistent' and not local as it will
> @@ -1544,15 +1550,16 @@ i915_gem_do_execbuffer(struct drm_device *dev, void *data,
>
>   	ret = dev_priv->gt.do_execbuf(params, args, &eb->vmas);
>
> +err:
>   	/*
>   	 * FIXME: We crucially rely upon the active tracking for the (ppgtt)
>   	 * batch vma for correctness. For less ugly and less fragility this
>   	 * needs to be adjusted to also track the ggtt batch vma properly as
>   	 * active.
>   	 */
> -	if (dispatch_flags & I915_DISPATCH_SECURE)
> +	if (batch_pinned)
>   		i915_gem_object_ggtt_unpin(batch_obj);
> -err:
> +
>   	/* the request owns the ref now */
>   	i915_gem_context_unreference(ctx);
>   	eb_destroy(eb);
>

Reviewed-by: Tomas Elf <tomas.elf at intel.com>

Thanks,
Tomas