[PATCH 1/3] dma-fence: Reserve 0 as a special NO_CONTEXT token

[Chris Wilson]

On Sat, Apr 08, 2017 at 07:49:37PM +0200, Christian König wrote:
> Am 08.04.2017 um 18:26 schrieb Chris Wilson:
> >Reserve 0 for general use a token meaning that the fence doesn't belong
> >to an ordered timeline (fence context).
> 
> NAK, we kept context allocation cheap to avoid exactly that.

However, they result in very sparse mappings.

> Please elaborate further why it should be necessary now.

Because I want to efficiently exclude them from comparisons as
demonstrated by this small series as there may be several hundred such
fences as dependencies for this job.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre