Re: [PATCH 08/10] drm/i915: Prelude to splitting i915_gem_do_execbuffer in two

Daniel Vetter
2014-12-10T10:57:31Z

On Tue, Dec 09, 2014 at 12:59:11PM +0000, John.C.Harrison@Intel.com wrote:
> From: John Harrison <John.C.Harrison@Intel.com>
>
> The scheduler decouples the submission of batch buffers to the driver with their
> submission to the hardware. This basically means splitting the execbuffer()
> function in half. This change rearranges some code ready for the split to occur.

Now there's the curios question: Where will the split in top/bottom halves
be? Without that I have no idea whether it makes sense and so can't review
this patch. At least if the goal is to really prep for the scheduler and
not just move a few lines around ;-)
-Daniel

>
> Change-Id: Icc9c8afaac18821f3eb8a151a49f918f90c068a3
> For: VIZ-1587
> Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
> ---
> drivers/gpu/drm/i915/i915_gem_execbuffer.c | 47 +++++++++++++++++-----------
> drivers/gpu/drm/i915/intel_lrc.c | 17 +++++++---
> 2 files changed, 40 insertions(+), 24 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
> index f09501c..a339556 100644
> --- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c
> +++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
> @@ -848,10 +848,7 @@ i915_gem_execbuffer_move_to_gpu(struct intel_engine_cs *ring,
> if (flush_domains & I915_GEM_DOMAIN_GTT)
> wmb();
>
> - /* Unconditionally invalidate gpu caches and ensure that we do flush
> - * any residual writes from the previous batch.
> - */
> - return intel_ring_invalidate_all_caches(ring);
> + return 0;
> }
>
> static bool
> @@ -1123,14 +1120,6 @@ i915_gem_ringbuffer_submission(struct drm_device *dev, struct drm_file *file,
> }
> }
>
> - ret = i915_gem_execbuffer_move_to_gpu(ring, vmas);
> - if (ret)
> - goto error;
> -
> - ret = i915_switch_context(ring, ctx);
> - if (ret)
> - goto error;
> -
> instp_mode = args->flags & I915_EXEC_CONSTANTS_MASK;
> instp_mask = I915_EXEC_CONSTANTS_MASK;
> switch (instp_mode) {
> @@ -1168,6 +1157,28 @@ i915_gem_ringbuffer_submission(struct drm_device *dev, struct drm_file *file,
> goto error;
> }
>
> + ret = i915_gem_execbuffer_move_to_gpu(ring, vmas);
> + if (ret)
> + goto error;
> +
> + i915_gem_execbuffer_move_to_active(vmas, ring);
> +
> + /* To be split into two functions here... */
> +
> + intel_runtime_pm_get(dev_priv);
> +
> + /* Unconditionally invalidate gpu caches and ensure that we do flush
> + * any residual writes from the previous batch.
> + */
> + ret = intel_ring_invalidate_all_caches(ring);
> + if (ret)
> + goto error;
> +
> + /* Switch to the correct context for the batch */
> + ret = i915_switch_context(ring, ctx);
> + if (ret)
> + goto error;
> +
> if (ring == &dev_priv->ring[RCS] &&
> instp_mode != dev_priv->relative_constants_mode) {
> ret = intel_ring_begin(ring, 4);
> @@ -1208,15 +1219,18 @@ i915_gem_ringbuffer_submission(struct drm_device *dev, struct drm_file *file,
> exec_start, exec_len,
> dispatch_flags);
> if (ret)
> - return ret;
> + goto error;
> }
>
> trace_i915_gem_ring_dispatch(intel_ring_get_request(ring), dispatch_flags);
>
> - i915_gem_execbuffer_move_to_active(vmas, ring);
> i915_gem_execbuffer_retire_commands(dev, file, ring, batch_obj);
>
> error:
> + /* intel_gpu_busy should also get a ref, so it will free when the device
> + * is really idle. */
> + intel_runtime_pm_put(dev_priv);
> +
> kfree(cliprects);
> return ret;
> }
> @@ -1335,8 +1349,6 @@ i915_gem_do_execbuffer(struct drm_device *dev, void *data,
> return -EINVAL;
> }
>
> - intel_runtime_pm_get(dev_priv);
> -
> ret = i915_mutex_lock_interruptible(dev);
> if (ret)
> goto pre_mutex_err;
> @@ -1467,9 +1479,6 @@ err:
> mutex_unlock(&dev->struct_mutex);
>
> pre_mutex_err:
> - /* intel_gpu_busy should also get a ref, so it will free when the device
> - * is really idle. */
> - intel_runtime_pm_put(dev_priv);
> return ret;
> }
>
> diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
> index 037cbd5..f16b15d 100644
> --- a/drivers/gpu/drm/i915/intel_lrc.c
> +++ b/drivers/gpu/drm/i915/intel_lrc.c
> @@ -630,10 +630,7 @@ static int execlists_move_to_gpu(struct intel_ringbuffer *ringbuf,
> if (flush_domains & I915_GEM_DOMAIN_GTT)
> wmb();
>
> - /* Unconditionally invalidate gpu caches and ensure that we do flush
> - * any residual writes from the previous batch.
> - */
> - return logical_ring_invalidate_all_caches(ringbuf);
> + return 0;
> }
>
> /**
> @@ -717,6 +714,17 @@ int intel_execlists_submission(struct drm_device *dev, struct drm_file *file,
> if (ret)
> return ret;
>
> + i915_gem_execbuffer_move_to_active(vmas, ring);
> +
> + /* To be split into two functions here... */
> +
> + /* Unconditionally invalidate gpu caches and ensure that we do flush
> + * any residual writes from the previous batch.
> + */
> + ret = logical_ring_invalidate_all_caches(ringbuf);
> + if (ret)
> + return ret;
> +
> if (ring == &dev_priv->ring[RCS] &&
> instp_mode != dev_priv->relative_constants_mode) {
> ret = intel_logical_ring_begin(ringbuf, 4);
> @@ -738,7 +746,6 @@ int intel_execlists_submission(struct drm_device *dev, struct drm_file *file,
>
> trace_i915_gem_ring_dispatch(intel_ring_get_request(ring), dispatch_flags);
>
> - i915_gem_execbuffer_move_to_active(vmas, ring);
> i915_gem_execbuffer_retire_commands(dev, file, ring, batch_obj);
>
> return 0;
> --
> 1.7.9.5
>
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--
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch