Re: [PATCH v4 10/38] drm/i915: Force MMIO flips when scheduler enabled

Daniel Vetter
2016-01-12T14:07:02Z

On Tue, Jan 12, 2016 at 11:19:26AM +0000, John Harrison wrote:
> On 11/01/2016 22:16, Chris Wilson wrote:
> >On Mon, Jan 11, 2016 at 06:42:39PM +0000, John.C.Harrison@Intel.com wrote:
> >>From: John Harrison <John.C.Harrison@Intel.com>
> >>
> >>MMIO flips are the preferred mechanism now but more importantly,
> >Says who?
>
> I asked this exact question at the linux architecture forum quite some time
> ago - does the scheduler need to worry about managing non-batch buffer work
> such as page flips. The answer from everyone present was no, MMIO flips are
> the way to go so don't over complicate the scheduler trying to support ring
> flips. Indeed, execlist mode already forces MMIO flips anyway.

Atomic will kill CS flips. We can mourn them and scream about the loss,
but imo best is to just skip that all and move on to acceptance. So mmio
flips (or well, atomic flips) is still the way to go for everything.
-Daniel
--
Daniel Vetter
Software Engineer, Intel Corporation