AW: [RFC 00/14] Deadline scheduler and other ideas

Wed Jan 8 17:59:56 UTC 2025

On Wed, Jan 08, 2025 at 09:07:44AM +0100, Philipp Stanner wrote:
> On Mon, 2025-01-06 at 14:47 +0100, Simona Vetter wrote:
> > On Fri, Jan 03, 2025 at 03:16:56PM +0000, Koenig, Christian wrote:
> > > [AMD Official Use Only - AMD Internal Distribution Only]
> > > 
> > > Could you send that whole patch set to me once more?
> > > 
> > > The AMD mails servers seem to have had a hickup over the holidays
> > > and
> > > all mails received between ~25.12.2024 and 1.1.2025 are somehow
> > > mangled.
> > 
> > I seem to have the same issue with fetching from lore.o.k, despite
> > that
> > the archives seem to be complete. No idea what's happened.
> 
> I could pull it just fine with b4

Yeah now they all just magically showed up. No idea what happened.
-Sima

> 
> P.
> 
> > -Sima
> > 
> > > 
> > > Thanks in advance,
> > > Christian.
> > > 
> > > ________________________________________
> > > Von: Tvrtko Ursulin <tursulin at igalia.com>
> > > Gesendet: Montag, 30. Dezember 2024 17:52
> > > An: dri-devel at lists.freedesktop.org
> > > Cc: kernel-dev at igalia.com; Tvrtko Ursulin; Koenig, Christian;
> > > Danilo Krummrich; Matthew Brost; Philipp Stanner
> > > Betreff: [RFC 00/14] Deadline scheduler and other ideas
> > > 
> > > From: Tvrtko Ursulin <tvrtko.ursulin at igalia.com>
> > > 
> > > <tldr>
> > > Replacing FIFO with a flavour of deadline driven scheduling and
> > > removing round-
> > > robin. Connecting the scheduler with dma-fence deadlines. First
> > > draft and
> > > testing by different drivers and feedback would be nice. I was only
> > > able to test
> > > it with amdgpu. Other drivers may not even compile.
> > > </tldr>
> > > 
> > > If I remember correctly Christian mentioned recently (give or take)
> > > that maybe
> > > round-robin could be removed. That got me thinking how and what
> > > could be
> > > improved and simplified. So I played a bit in the scheduler code
> > > and came up
> > > with something which appears to not crash at least. Whether or not
> > > there are
> > > significant advantages apart from maybe code consolidation and
> > > reduction is the
> > > main thing to be determined.
> > > 
> > > One big question is whether round-robin can really be removed. Does
> > > anyone use
> > > it, rely on it, or what are even use cases where it is much better
> > > than FIFO.
> > > 
> > > See "drm/sched: Add deadline policy" commit message for a short
> > > description on
> > > what flavour of deadline scheduling it is. But in essence it should
> > > a more fair
> > > FIFO where higher priority can not forever starve lower priorities.
> > > 
> > > "drm/sched: Connect with dma-fence deadlines" wires up dma-fence
> > > deadlines to
> > > the scheduler because it is easy and makes logical sense with this.
> > > And I
> > > noticed userspace already uses it so why not wire it up fully.
> > > 
> > > Otherwise the series is a bit of progression from consolidating RR
> > > into FIFO
> > > code paths and going from there to deadline and then to a change in
> > > how
> > > dependencies are handled. And code simplification to 1:1 run queue
> > > to scheduler
> > > relationship, because deadline does not need per priority run
> > > queues.
> > > 
> > > There is quite a bit of code to go throught here so I think it
> > > could be even
> > > better if other drivers could give it a spin as is and see if some
> > > improvements
> > > can be detected. Or at least no regressions.
> > > 
> > > Cc: Christian König <christian.koenig at amd.com>
> > > Cc: Danilo Krummrich <dakr at redhat.com>
> > > Cc: Matthew Brost <matthew.brost at intel.com>
> > > Cc: Philipp Stanner <pstanner at redhat.com>
> > > 
> > > Tvrtko Ursulin (14):
> > >   drm/sched: Delete unused update_job_credits
> > >   drm/sched: Remove idle entity from tree
> > >   drm/sched: Implement RR via FIFO
> > >   drm/sched: Consolidate entity run queue management
> > >   drm/sched: Move run queue related code into a separate file
> > >   drm/sched: Ignore own fence earlier
> > >   drm/sched: Resolve same scheduler dependencies earlier
> > >   drm/sched: Add deadline policy
> > >   drm/sched: Remove FIFO and RR and simplify to a single run queue
> > >   drm/sched: Queue all free credits in one worker invocation
> > >   drm/sched: Connect with dma-fence deadlines
> > >   drm/sched: Embed run queue singleton into the scheduler
> > >   dma-fence: Add helper for custom fence context when merging
> > > fences
> > >   drm/sched: Resolve all job dependencies in one go
> > > 
> > >  drivers/dma-buf/dma-fence-unwrap.c          |   8 +-
> > >  drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c      |   6 +-
> > >  drivers/gpu/drm/amd/amdgpu/amdgpu_job.c     |  27 +-
> > >  drivers/gpu/drm/amd/amdgpu/amdgpu_job.h     |   5 +-
> > >  drivers/gpu/drm/amd/amdgpu/amdgpu_trace.h   |   8 +-
> > >  drivers/gpu/drm/amd/amdgpu/amdgpu_vm_sdma.c |   8 +-
> > >  drivers/gpu/drm/amd/amdgpu/amdgpu_xcp.c     |   8 +-
> > >  drivers/gpu/drm/scheduler/Makefile          |   2 +-
> > >  drivers/gpu/drm/scheduler/sched_entity.c    | 316 ++++++-----
> > >  drivers/gpu/drm/scheduler/sched_fence.c     |   5 +-
> > >  drivers/gpu/drm/scheduler/sched_main.c      | 587 +++++-----------
> > > ----
> > >  drivers/gpu/drm/scheduler/sched_rq.c        | 199 +++++++
> > >  include/drm/gpu_scheduler.h                 |  74 ++-
> > >  include/linux/dma-fence-unwrap.h            |  31 +-
> > >  14 files changed, 606 insertions(+), 678 deletions(-)
> > >  create mode 100644 drivers/gpu/drm/scheduler/sched_rq.c
> > > 
> > > --
> > > 2.47.1
> > > 
> > 
> 

-- 
Simona Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch