Re: [PATCH v9 15/15] drm/i915: Add deadline based boost support

Matt Turner
2023-03-03T18:20:54Z

On Fri, Mar 3, 2023 at 10:08 AM Tvrtko Ursulin
<tvrtko.ursulin@linux.intel.com> wrote:
>
>
> On 03/03/2023 14:48, Rob Clark wrote:
> > On Fri, Mar 3, 2023 at 1:58 AM Tvrtko Ursulin
> > <tvrtko.ursulin@linux.intel.com> wrote:
> >>
> >>
> >> On 03/03/2023 03:21, Rodrigo Vivi wrote:
> >>> On Thu, Mar 02, 2023 at 03:53:37PM -0800, Rob Clark wrote:
> >>>> From: Rob Clark <robdclark@chromium.org>
> >>>>
> >>>
> >>> missing some wording here...
> >>>
> >>>> v2: rebase
> >>>>
> >>>> Signed-off-by: Rob Clark <robdclark@chromium.org>
> >>>> ---
> >>>> drivers/gpu/drm/i915/i915_request.c | 20 ++++++++++++++++++++
> >>>> 1 file changed, 20 insertions(+)
> >>>>
> >>>> diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/drm/i915/i915_request.c
> >>>> index 7503dcb9043b..44491e7e214c 100644
> >>>> --- a/drivers/gpu/drm/i915/i915_request.c
> >>>> +++ b/drivers/gpu/drm/i915/i915_request.c
> >>>> @@ -97,6 +97,25 @@ static bool i915_fence_enable_signaling(struct dma_fence *fence)
> >>>> return i915_request_enable_breadcrumb(to_request(fence));
> >>>> }
> >>>>
> >>>> +static void i915_fence_set_deadline(struct dma_fence *fence, ktime_t deadline)
> >>>> +{
> >>>> + struct i915_request *rq = to_request(fence);
> >>>> +
> >>>> + if (i915_request_completed(rq))
> >>>> + return;
> >>>> +
> >>>> + if (i915_request_started(rq))
> >>>> + return;
> >>>
> >>> why do we skip the boost if already started?
> >>> don't we want to boost the freq anyway?
> >>
> >> I'd wager Rob is just copying the current i915 wait boost logic.
> >
> > Yup, and probably incorrectly.. Matt reported fewer boosts/sec
> > compared to your RFC, this could be the bug
>
> Hm, there I have preserved this same !i915_request_started logic.
>
> Presumably it's not just fewer boosts but lower performance. How is he
> setting the deadline? Somehow from clFlush or so?
>
> Regards,
>
> Tvrtko
>
> P.S. Take note that I did not post the latest version of my RFC. The one
> where I fix the fence chain and array misses you pointed out. I did not
> think it would be worthwhile given no universal love for it, but if
> people are testing with it more widely that I was aware perhaps I should.

Yep, that would be great. We're interested in it for ChromeOS. Please
Cc me on the series when you send it.