On Sat, Apr 16, 2011 at 03:18:46PM +0100, Chris Wilson wrote:
> On Sat, 16 Apr 2011 15:54:56 +0200, Daniel Vetter <dan...@ffwll.ch> wrote:
> > On Sat, Apr 16, 2011 at 10:17:42AM +0100, Chris Wilson wrote:
> > > As we can make use of the ability to insert semaphores to serialise
> > > accessing buffers between ring elsewhere, separate out the function from
> > > the execbuffer code and make it generic.
> >
> > Perhaps add a small note somewhere that move_to_ring now does the right
> > thing when to == NULL (falling back to wait_rendering). I've hunted around
> > a bit for that ...
>
> /**
> * Serialise an object between rings: wait for it to complete on the first
> * ring, before it can be used on the next.
> *
> * If the object is staying on the same ring, this is a no-op.
> *
> * If the object is not currently on a ring, this is a no-op.
> *
> * If the object is moving off a ring (i.e. to == NULL), then we wait for
> * rendering to complete entirely.
> *
> * The interesting case is when we move between two different rings. On
> * pre-SandyBridge hw, we have no choice but to wait until rendering has
> * finished. SandyBridge, however introduces the GPU semaphore which we
> * can use to cause one ring to wait upon the signal of another - avoiding
> * the CPU stall.
> *
> * We assume that the caller has emitted all required flushes.
> */
Perfect!
-Daniel
--
Daniel Vetter
Mail: dan...@ffwll.ch
Mobile: +41 (0)79 365 57 48
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