On Mon, May 05, 2014 at 01:07:32AM -0700, Chris Wilson wrote:
> A few improvements to the fallback method for waiting upon ring space:
>
> 1. Fix the start/end wait tracepoints to always be paired.
> 2. Increase responsiveness of checking
> 3. Mark the process as waiting upon io
> 4. Check for signal interruptions
>
> Signed-off-by: Chris Wilson <ch...@chris-wilson.co.uk>
These seem like reasonable improvements.
Reviewed-by: Brad Volkin <bradley.d.vol...@intel.com>
> ---
> drivers/gpu/drm/i915/intel_ringbuffer.c | 24 +++++++++++++++++-------
> 1 file changed, 17 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c
> b/drivers/gpu/drm/i915/intel_ringbuffer.c
> index e0c7bf27eafd..d6b7b884adf9 100644
> --- a/drivers/gpu/drm/i915/intel_ringbuffer.c
> +++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
> @@ -1546,7 +1546,6 @@ static int ring_wait_for_space(struct intel_ring_buffer
> *ring, int n)
> /* force the tail write in case we have been skipping them */
> __intel_ring_advance(ring);
>
> - trace_i915_ring_wait_begin(ring);
> /* With GEM the hangcheck timer should kick us out of the loop,
> * leaving it early runs the risk of corrupting GEM state (due
> * to running on almost untested codepaths). But on resume
> @@ -1554,12 +1553,13 @@ static int ring_wait_for_space(struct
> intel_ring_buffer *ring, int n)
> * case by choosing an insanely large timeout. */
> end = jiffies + 60 * HZ;
>
> + trace_i915_ring_wait_begin(ring);
> do {
> ring->head = I915_READ_HEAD(ring);
> ring->space = ring_space(ring);
> if (ring->space >= n) {
> - trace_i915_ring_wait_end(ring);
> - return 0;
> + ret = 0;
> + break;
> }
>
> if (!drm_core_check_feature(dev, DRIVER_MODESET) &&
> @@ -1569,15 +1569,25 @@ static int ring_wait_for_space(struct
> intel_ring_buffer *ring, int n)
> master_priv->sarea_priv->perf_boxes |=
> I915_BOX_WAIT;
> }
>
> - msleep(1);
> + io_schedule_timeout(1);
> +
> + if (dev_priv->mm.interruptible && signal_pending(current)) {
> + ret = -ERESTARTSYS;
> + break;
> + }
>
> ret = i915_gem_check_wedge(&dev_priv->gpu_error,
> dev_priv->mm.interruptible);
> if (ret)
> - return ret;
> - } while (!time_after(jiffies, end));
> + break;
> +
> + if (time_after(jiffies, end)) {
> + ret = -EBUSY;
> + break;
> + }
> + } while (1);
> trace_i915_ring_wait_end(ring);
> - return -EBUSY;
> + return ret;
> }
>
> static int intel_wrap_ring_buffer(struct intel_ring_buffer *ring)
> --
> 2.0.0.rc0
>
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