Re: [PATCH 17/48] drm/i915: Track which ring a context ran on

Chris Wilson
2014-04-18T09:51:57Z

On Fri, Dec 06, 2013 at 02:11:02PM -0800, Ben Widawsky wrote:
> From: Ben Widawsky <ben@bwidawsk.net>
>
> Previously we dropped the association of a context to a ring. It is
> however very important to know which ring a context ran on (we could
> have reused the other member, but I was nitpicky).
>
> This is very important when we switch address spaces, which unlike
> context objects, do change per ring.
>
> As an example, if we have:
>
> RCS BCS
> ctx A
> ctx A
> ctx B
> ctx B
>
> Without tracking the last ring B ran on, we wouldn't know to switch the
> address space on BCS in the last row.
>
> As a result, we no longer need to track which ring a context "belongs"
> to, as it never really made much sense anyway.

What about ring->last_context != to? That would force the update on BCS
from A to B.
-Chris

--
Chris Wilson, Intel Open Source Technology Centre