From: "Christian König" <christian.koenig@amd.com>
To: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: DRI Development <dri-devel@lists.freedesktop.org>,
Intel Graphics Development <intel-gfx@lists.freedesktop.org>,
Lucas Stach <l.stach@pengutronix.de>,
Melissa Wen <mwen@igalia.com>,
Daniel Vetter <daniel.vetter@intel.com>,
Luben Tuikov <luben.tuikov@amd.com>,
Andrey Grodzovsky <andrey.grodzovsky@amd.com>,
Alex Deucher <alexander.deucher@amd.com>
Subject: Re: [Intel-gfx] [PATCH v5 14/20] drm/sched: Don't store self-dependencies
Date: Thu, 5 Aug 2021 15:57:05 +0200 [thread overview]
Message-ID: <32f5f17d-9c2b-c6e3-9809-4100bcadf21c@amd.com> (raw)
In-Reply-To: <CAKMK7uEVbTOuJVvQDybFM+9x4LUP+ojcCzWfkp4sau3oX7fjXQ@mail.gmail.com>
Am 05.08.21 um 15:25 schrieb Daniel Vetter:
> On Thu, Aug 5, 2021 at 3:18 PM Christian König <christian.koenig@amd.com> wrote:
>>
>>
>> Am 05.08.21 um 12:46 schrieb Daniel Vetter:
>>> This is essentially part of drm_sched_dependency_optimized(), which
>>> only amdgpu seems to make use of. Use it a bit more.
>>>
>>> This would mean that as-is amdgpu can't use the dependency helpers, at
>>> least not with the current approach amdgpu has for deciding whether a
>>> vm_flush is needed. Since amdgpu also has very special rules around
>>> implicit fencing it can't use those helpers either, and adding a
>>> drm_sched_job_await_fence_always or similar for amdgpu wouldn't be too
>>> onerous. That way the special case handling for amdgpu sticks even
>>> more out and we have higher chances that reviewers that go across all
>>> drivers wont miss it.
>> Well you should probably drop the sentence about the vm_flush, this is
>> completely unrelated.
>>
>> Additional to that I still don't think that this is a good idea.
>> Dependency handling is something completely driver specific.
>>
>> E.g. even when you have submitted jobs back to back they still might
>> need a cache flush in between and that is not only for amdgpu like this.
>>
>> What you can do is to optimize for while looking at the fences later on
>> and then note that you have done so and what the last hw fence is you
>> used instead.
> Out of 6 drivers using drm/sched 5 can use this. When we get i915
> over, that one will be added to the list. amdgpu can't use any of this
> anyway due to the vm_id allocation requirements, which is why I
> mention that. Also note that all the callbacks are still there, so you
> can just ignore this all and still build your own. Like amdgpu does.
The VMID allocation stuff is rather easy to handle, that's why I noted
we should remove that sentence.
The problematic stuff is handling the cache flush and pipeline sync
which you make impossible with this here.
> So I'm not sure what exactly your object is, aside from "this doesn't
> fit for amdgpu", which a) I know b) the commit message explains c)
> doesn't actually hurt amdgpu in the slightest. And we still get the
> benefit that for most drivers it's a nice optimization.
Well exactly that's what I wanted to avoid. We still can use this in
amdgpu even with the VMID allocation stuff and I still hope to do so.
Can't we add this as a wrapper or similar?
Christian.
> -Daniel
>
>> Regards,
>> Christian.
>>
>>> Reviewed-by: Lucas Stach <l.stach@pengutronix.de>
>>> Acked-by: Melissa Wen <mwen@igalia.com>
>>> Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
>>> Cc: "Christian König" <christian.koenig@amd.com>
>>> Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
>>> Cc: Luben Tuikov <luben.tuikov@amd.com>
>>> Cc: Andrey Grodzovsky <andrey.grodzovsky@amd.com>
>>> Cc: Alex Deucher <alexander.deucher@amd.com>
>>> ---
>>> drivers/gpu/drm/scheduler/sched_main.c | 7 +++++++
>>> 1 file changed, 7 insertions(+)
>>>
>>> diff --git a/drivers/gpu/drm/scheduler/sched_main.c b/drivers/gpu/drm/scheduler/sched_main.c
>>> index f77456929139..49e507f91ec0 100644
>>> --- a/drivers/gpu/drm/scheduler/sched_main.c
>>> +++ b/drivers/gpu/drm/scheduler/sched_main.c
>>> @@ -660,6 +660,13 @@ int drm_sched_job_add_dependency(struct drm_sched_job *job,
>>> if (!fence)
>>> return 0;
>>>
>>> + /* if it's a fence from us it's guaranteed to be earlier */
>>> + if (fence->context == job->entity->fence_context ||
>>> + fence->context == job->entity->fence_context + 1) {
>>> + dma_fence_put(fence);
>>> + return 0;
>>> + }
>>> +
>>> /* Deduplicate if we already depend on a fence from the same context.
>>> * This lets the size of the array of deps scale with the number of
>>> * engines involved, rather than the number of BOs.
>
next prev parent reply other threads:[~2021-08-05 13:57 UTC|newest]
Thread overview: 65+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-05 10:46 [Intel-gfx] [PATCH v5 00/20] drm/sched dependency handling and implicit sync fixes Daniel Vetter
2021-08-05 10:46 ` [Intel-gfx] [PATCH v5 01/20] drm/sched: Split drm_sched_job_init Daniel Vetter
2021-08-05 13:43 ` Christian König
2021-08-05 14:07 ` Daniel Vetter
2021-08-05 14:47 ` Christian König
2021-08-05 15:07 ` Daniel Vetter
2021-08-17 8:49 ` [Intel-gfx] [PATCH] " Daniel Vetter
2021-08-05 10:46 ` [Intel-gfx] [PATCH v5 02/20] drm/msm: Fix drm/sched point of no return rules Daniel Vetter
2021-08-05 23:02 ` Rob Clark
2021-08-06 16:41 ` Daniel Vetter
2021-08-06 17:19 ` Rob Clark
2021-08-06 18:41 ` Daniel Vetter
2021-08-06 19:01 ` Rob Clark
2021-08-06 19:10 ` Daniel Vetter
2021-08-06 19:59 ` Rob Clark
2021-08-17 8:53 ` [Intel-gfx] [PATCH] drm/msm: Improve " Daniel Vetter
2021-08-26 9:33 ` Daniel Vetter
2021-08-26 15:38 ` Rob Clark
2021-08-05 10:46 ` [Intel-gfx] [PATCH v5 03/20] drm/sched: Barriers are needed for entity->last_scheduled Daniel Vetter
2021-08-05 13:45 ` Christian König
2021-08-05 10:46 ` [Intel-gfx] [PATCH v5 04/20] drm/sched: Add dependency tracking Daniel Vetter
2021-08-05 13:47 ` Christian König
2021-08-05 10:46 ` [Intel-gfx] [PATCH v5 05/20] drm/sched: drop entity parameter from drm_sched_push_job Daniel Vetter
2021-08-05 13:48 ` Christian König
2021-08-05 10:46 ` [Intel-gfx] [PATCH v5 06/20] drm/sched: improve docs around drm_sched_entity Daniel Vetter
2021-08-05 10:46 ` [Intel-gfx] [PATCH v5 07/20] drm/panfrost: use scheduler dependency tracking Daniel Vetter
2021-08-05 15:10 ` Alyssa Rosenzweig
2021-08-05 10:46 ` [Intel-gfx] [PATCH v5 08/20] drm/lima: " Daniel Vetter
2021-08-12 19:28 ` Daniel Vetter
2021-08-14 2:45 ` Qiang Yu
2021-08-05 10:46 ` [Intel-gfx] [PATCH v5 09/20] drm/v3d: Move drm_sched_job_init to v3d_job_init Daniel Vetter
2021-08-05 10:46 ` [Intel-gfx] [PATCH v5 10/20] drm/v3d: Use scheduler dependency handling Daniel Vetter
2021-08-05 10:46 ` [Intel-gfx] [PATCH v5 11/20] drm/etnaviv: " Daniel Vetter
2021-08-12 19:28 ` Daniel Vetter
2021-08-05 10:46 ` [Intel-gfx] [PATCH v5 12/20] drm/msm: " Daniel Vetter
2021-08-12 19:29 ` Daniel Vetter
2021-08-26 16:12 ` Rob Clark
2021-08-30 9:01 ` Daniel Vetter
2021-08-05 10:46 ` [Intel-gfx] [PATCH v5 13/20] drm/gem: Delete gem array fencing helpers Daniel Vetter
2021-08-12 19:29 ` Daniel Vetter
2021-08-05 10:46 ` [Intel-gfx] [PATCH v5 14/20] drm/sched: Don't store self-dependencies Daniel Vetter
2021-08-05 13:18 ` Christian König
2021-08-05 13:25 ` Daniel Vetter
2021-08-05 13:57 ` Christian König [this message]
2021-08-05 15:06 ` Daniel Vetter
2021-08-05 10:47 ` [Intel-gfx] [PATCH v5 15/20] drm/sched: Check locking in drm_sched_job_await_implicit Daniel Vetter
2021-08-05 13:19 ` Christian König
2021-08-05 13:27 ` Daniel Vetter
2021-08-05 10:47 ` [Intel-gfx] [PATCH v5 16/20] drm/msm: Don't break exclusive fence ordering Daniel Vetter
2021-08-26 16:16 ` Rob Clark
2021-08-30 9:02 ` Daniel Vetter
2021-08-05 10:47 ` [Intel-gfx] [PATCH v5 17/20] drm/etnaviv: " Daniel Vetter
2021-08-05 10:47 ` [Intel-gfx] [PATCH v5 18/20] drm/i915: delete exclude argument from i915_sw_fence_await_reservation Daniel Vetter
2021-08-05 10:47 ` [Intel-gfx] [PATCH v5 19/20] drm/i915: Don't break exclusive fence ordering Daniel Vetter
2021-08-05 10:47 ` [Intel-gfx] [PATCH v5 20/20] dma-resv: Give the docs a do-over Daniel Vetter
2021-08-30 19:38 ` Daniel Vetter
2021-08-05 13:58 ` [Intel-gfx] ✗ Fi.CI.CHECKPATCH: warning for drm/sched dependency handling and implicit sync fixes Patchwork
2021-08-05 14:29 ` [Intel-gfx] ✗ Fi.CI.BAT: failure " Patchwork
2021-08-06 19:14 ` [Intel-gfx] ✗ Fi.CI.BUILD: failure for drm/sched dependency handling and implicit sync fixes (rev2) Patchwork
2021-08-17 16:27 ` [Intel-gfx] ✗ Fi.CI.CHECKPATCH: warning for drm/sched dependency handling and implicit sync fixes (rev4) Patchwork
2021-08-17 16:57 ` [Intel-gfx] ✓ Fi.CI.BAT: success " Patchwork
2021-08-17 18:15 ` [Intel-gfx] ✗ Fi.CI.IGT: failure " Patchwork
2021-08-26 13:17 ` [Intel-gfx] ✗ Fi.CI.CHECKPATCH: warning for drm/sched dependency handling and implicit sync fixes (rev5) Patchwork
2021-08-26 13:48 ` [Intel-gfx] ✓ Fi.CI.BAT: success " Patchwork
2021-08-26 21:46 ` [Intel-gfx] ✗ Fi.CI.IGT: failure " Patchwork
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