| From: |
| Philipp Stanner <phasta-AT-kernel.org> |
| To: |
| Matthew Brost <matthew.brost-AT-intel.com>, Danilo Krummrich <dakr-AT-kernel.org>, Philipp Stanner <phasta-AT-kernel.org>, Christian König <ckoenig.leichtzumerken-AT-gmail.com>, Maarten Lankhorst <maarten.lankhorst-AT-linux.intel.com>, Maxime Ripard <mripard-AT-kernel.org>, Thomas Zimmermann <tzimmermann-AT-suse.de>, David Airlie <airlied-AT-gmail.com>, Simona Vetter <simona-AT-ffwll.ch>, Sumit Semwal <sumit.semwal-AT-linaro.org>, Marco Pagani <marco.pagani-AT-linux.dev>, Tvrtko Ursulin <tvrtko.ursulin-AT-igalia.com>, Boris Brezillon <boris.brezillon-AT-collabora.com> |
| Subject: |
| [PATCH 0/5] drm/sched: Introduce the miracle of locking to entity |
| Date: |
| Wed, 01 Jul 2026 10:59:16 +0200 |
| Message-ID: |
| <20260701085920.3253248-2-phasta@kernel.org> |
| Cc: |
| dri-devel-AT-lists.freedesktop.org, linux-kernel-AT-vger.kernel.org, linux-media-AT-vger.kernel.org, linaro-mm-sig-AT-lists.linaro.org |
| Archive-link: |
| Article |
Both Tvrtko [1] and I [2] have recently proposed some improvals for
drm_sched.
While taking Tvrtko's feedback into account for my patch, I realized
that both his and my patch can be fully replaced with a bigger and far
more beautiful series.
If I am not mistaken, it turns out that the entire entity->entity_idle
completion is also nothing but a workaround around the grave mistake of
not using the greatest helper with parallel programming that exists in
computer science: Locking.
This series adds locking to the last_scheduled field and all checks
related to detect the idleness of the entity. As before, the
job_scheduled event queue causes the periodic checks.
This way, we can get rid of memory barriers, RCU, a few lines of code,
make things more readable, understandable...
Tested with drm-sched-unit tests. I'm a bit busy right now, but wanted
to show you guys the idea. Before merging I'd test it more exhaustively
with Nouveau.
Greetings,
Philipp
[1] https://lore.kernel.org/dri-devel/20260611123423.39819-1-...
[2] https://lore.kernel.org/dri-devel/20260626081942.2122144-...
Philipp Stanner (5):
drm/sched: Protect entity->last_scheduled with spinlock
drm/sched: Lock spsc_queue in drm_sched_entity_pop_job()
drm/sched: Avoid lock cycle for sched_entity
drm/sched: Lock drm_sched_entity_is_idle()
drm/sched: Remove entity->entity_idle
drivers/gpu/drm/scheduler/sched_entity.c | 75 +++++++++++-------------
drivers/gpu/drm/scheduler/sched_main.c | 2 -
drivers/gpu/drm/scheduler/sched_rq.c | 5 +-
include/drm/gpu_scheduler.h | 16 ++---
4 files changed, 41 insertions(+), 57 deletions(-)
base-commit: be4f10d44757211fd656fa57f37034657f26c883
--
2.54.0
