[Intel-gfx] [RFC PATCH 00/11] i915 HW context support

[Ben Widawsky]

On Thu, 16 Feb 2012 13:04:14 +0100
Ben Widawsky <ben at bwidawsk.net> wrote:

> On Wed, 15 Feb 2012 12:33:38 -0800
> Eric Anholt <eric at anholt.net> wrote:
> 
> > On Tue, 14 Feb 2012 22:09:07 +0100, Ben Widawsky <ben at bwidawsk.net> wrote:
> > > These patches are a heavily revised version of the patches I wrote over
> > > a year ago. These patches have passed basic tests on SNB, and IVB, and
> > > older versions worked on ILK.  In theory, context support should work
> > > all the way back to Gen4, but I haven't tested it. Also since I suspect
> > > ILK may be unstable, so the code has it disabled for now.
> > > 
> > > HW contexts provide a way for the GPU to save an restore certain state
> > > in between batchbuffer boundaries. Typically, GPU clients must re-emit
> > > the entire state every time they run because the client does not know
> > > what has been destroyed since the last time. With these patches the
> > > driver will emit special instructions to do this on behalf of the client
> > > if it has registered a context, and included that with the batchbuffer.
> > 
> > These patches look pretty solid.  In particular, the API
> > (create/destroy/context id in execbuf) looks like just what we want for
> > Mesa.  I'll try to get around to testing it out soon (I'm poking at some
> > performance stuff currently where this might become relevant soon).
> 
> I've just started noticing GPU hangs with Ken's test mesa branch on
> nexuiz with vsync, full 13x7 and max effects.  It seems to work fine 
> with variations like windowed, lower detail, etc. Although it looks
> weird on IVB, I cannot reproduce the hangs there. Also, I'd never seen 
> the hangs before this morning, and I'm not sure what has changed. So 
> FYI, you may want to start out with IVB (unless you want to help me 
> figure out what is broken on SNB :-)
> 
> I've not tried very hard, but so far it only seems to occur when doing
> context switches, however MI_SET_CONTEXT is nowhere in the error state.

Seems like sandybridge + fullscreen nexuiz is the exact fail combo.

> 
> > 
> > The couple of patches without a comment from me are:
> > 
> > Reviewed-by: Eric Anholt <eric at anholt.net>
> > 
>