Re: [PATCH v9 15/15] drm/i915: Add deadline based boost support
From: Tvrtko Ursulin
Date: Fri Mar 03 2023 - 10:08:33 EST
On 03/03/2023 14:48, Rob Clark wrote:
On Fri, Mar 3, 2023 at 1:58 AM Tvrtko Ursulin
<tvrtko.ursulin@xxxxxxxxxxxxxxx> 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@xxxxxxxxxxxx>
missing some wording here...
v2: rebase
Signed-off-by: Rob Clark <robdclark@xxxxxxxxxxxx>
---
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.
+
+ /*
+ * TODO something more clever for deadlines that are in the
+ * future. I think probably track the nearest deadline in
+ * rq->timeline and set timer to trigger boost accordingly?
+ */
I'm afraid it will be very hard to find some heuristics of what's
late enough for the boost no?
I mean, how early to boost the freq on an upcoming deadline for the
timer?
We can off load this patch from Rob and deal with it separately, or
after the fact?
That is completely my intention, I expect you to replace my i915 patch ;-)
Rough idea when everyone is happy with the core bits is to setup an
immutable branch without the driver specific patches, which could be
merged into drm-next and $driver-next and then each driver team can
add there own driver patches on top
BR,
-R
It's a half solution without a smarter scheduler too. Like
https://lore.kernel.org/all/20210208105236.28498-10-chris@xxxxxxxxxxxxxxxxxx/,
or if GuC plans to do something like that at any point.
Or bump the priority too if deadline is looming?
IMO it is not very effective to fiddle with the heuristic on an ad-hoc
basis. For instance I have a new heuristics which improves the
problematic OpenCL cases for further 5% (relative to the current
waitboost improvement from adding missing syncobj waitboost). But I
can't really test properly for regressions over platforms, stacks,
workloads.. :(
Regards,
Tvrtko
+
+ intel_rps_boost(rq);
+}
+
static signed long i915_fence_wait(struct dma_fence *fence,
bool interruptible,
signed long timeout)
@@ -182,6 +201,7 @@ const struct dma_fence_ops i915_fence_ops = {
.signaled = i915_fence_signaled,
.wait = i915_fence_wait,
.release = i915_fence_release,
+ .set_deadline = i915_fence_set_deadline,
};
static void irq_execute_cb(struct irq_work *wrk)
--
2.39.1