Re: [PATCH 26/53] drm/i915/bdw: New logical ring submission mechanism

[Daniel Vetter <daniel@ffwll.ch>]

On Tue, Jun 24, 2014 at 12:29:45PM +0000, Mateo Lozano, Oscar wrote:
> > -----Original Message-----
> > From: Volkin, Bradley D
> > Sent: Monday, June 23, 2014 8:10 PM
> > To: Mateo Lozano, Oscar
> > Cc: Chris Wilson; intel-gfx@lists.freedesktop.org
> > Subject: Re: [Intel-gfx] [PATCH 26/53] drm/i915/bdw: New logical ring
> > submission mechanism
> > There are 3 cases of non-execbuffer submissions that I can think of: flips,
> > render state, and clear-buffer (proposed patches on the list). I wonder if the
> > right approach might be to use batchbuffers with a small wrapper around the
> > dispatch_execbuffer/emit_bb_start vfuncs. Basically the rule would be to
> > only touch a ringbuffer from within the intel_engine_cs vfuncs, which always
> > know which set of functions to use.
> > 
> > For flips, we could use MMIO flips. Render state already uses the existing
> > dispatch_execbuffer() and add_request(). The clear code could potentially do
> > the same. There would obviously be some overhead in using a batch buffer
> > for what could end up being just a few commands. Perhaps the batch buffer
> > pool code from the command parser would help though.
> 
> This has another positive side-effect: the scheduler guys do not like
> things inside the ring without a proper batchbuffer & request, because
> it makes their life more complex.

I'm probably missing all the context here but I've thought this is the
plan forward: We'll use mmio flips with execlists and otherwise we'll
submit everything with the right context/engine whaterever using
execlist-specific functions.

Since the gpu clear code isn't merged yet we can imo ignore it for now and
merge execlists first.
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch