Re: [PATCH] drm/i915: disable flushing_list/gpu_write_list

[Chris Wilson <chris@chris-wilson.co.uk>]

On Wed, 13 Jun 2012 20:45:19 +0200, Daniel Vetter <daniel.vetter@ffwll.ch> wrote:
> This is just the minimal patch to disable all this code so that we can
> do decent amounts of QA before we rip it all out.
> 
> The complicating thing is that we need to flush the gpu caches after
> the batchbuffer is emitted. Which is past the point of no return where
> execbuffer can't fail any more (otherwise we risk submitting the same
> batch multiple times).
> 
> Hence we need to add a flag to track whether any caches associated
> with that ring are dirty. And emit the flush in add_request if that's
> the case.
> 
> Note that this has a quite a few behaviour changes:
> - Caches get flushed/invalidated unconditionally.
> - Invalidation now happens after potential inter-ring sync.
> 
> I've bantered around a bit with Chris on irc whether this fixes
> anything, and it might or might not. The only thing clear is that with
> these changes it's much easier to reason about correctness.
> 
> Also rip out a lone get_next_request_seqno in the execbuffer
> retire_commands function. I've dug around and I couldn't figure out
> why that is still there, with the outstanding lazy request stuff it
> shouldn't be necessary.
> 
> v2: Chris Wilson complained that I also invalidate the read caches
> when flushing after a batchbuffer. Now optimized.
> 
> v3: Added some comments to explain the new flushing behaviour.
> 
> Cc: Eric Anholt <eric@anholt.net>
> Cc: Chris Wilson <chris@chris-wilson.co.uk>
> Signed-Off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

This seems to work fine for 2D workloads, so
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>

I'll follow up in a few days with a tested-by if nothing untoward
happens.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre