Re: [PATCH 6.12.y 1/3] drm/sched: Optimise drm_sched_entity_push_job

["Jules Maselbas" <jmaselbas@zdiv.net>]

On Mon Sep 22, 2025 at 7:39 PM CEST, Christian König wrote:
> On 22.09.25 17:30, Philipp Stanner wrote:
>> On Mon, 2025-09-22 at 15:09 +0200, Jules Maselbas wrote:
>>> From: Tvrtko Ursulin <tvrtko.ursulin@igalia.com>
>>>
>>> commit d42a254633c773921884a19e8a1a0f53a31150c3 upstream.
>>>
>>> In FIFO mode (which is the default), both drm_sched_entity_push_job() and
>>> drm_sched_rq_update_fifo(), where the latter calls the former, are
>>> currently taking and releasing the same entity->rq_lock.
>>>
>>> We can avoid that design inelegance, and also have a miniscule
>>> efficiency improvement on the submit from idle path, by introducing a new
>>> drm_sched_rq_update_fifo_locked() helper and pulling up the lock taking to
>>> its callers.
>>>
>>> v2:
>>>  * Remove drm_sched_rq_update_fifo() altogether. (Christian)
>>>
>>> v3:
>>>  * Improved commit message. (Philipp)
>>>
>>> Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@igalia.com>
>>> Cc: Christian König <christian.koenig@amd.com>
>>> Cc: Alex Deucher <alexander.deucher@amd.com>
>>> Cc: Luben Tuikov <ltuikov89@gmail.com>
>>> Cc: Matthew Brost <matthew.brost@intel.com>
>>> Cc: Philipp Stanner <pstanner@redhat.com>
>>> Reviewed-by: Christian König <christian.koenig@amd.com>
>>> Signed-off-by: Philipp Stanner <pstanner@redhat.com>
>>> Link: https://patchwork.freedesktop.org/patch/msgid/20241016122013.7857-2-tursulin@igalia.com
>>> (cherry picked from commit d42a254633c773921884a19e8a1a0f53a31150c3)
>>> Signed-off-by: Jules Maselbas <jmaselbas@zdiv.net>
>> 
>> Am I interpreting this mail correctly: you want to get this patch into
>> stable?
>> 
>> Why? It doesn't fix a bug.
>
> Patch #3 in this series depends on the other two, but I agree that isn't a good idea.
Yes patch #3 fixes a freeze in amdgpu

> We should just adjust patch #3 to apply on the older kernel as well instead of backporting patches #1 and #2.
I initially modified patch #3 to use .rq_lock instead of .lock, but i didn't felt very confident with this modification.
Should i sent a new version with a modified patch #3 ?
If so, how the change should be reflected in the commit message ?
(I initially ask #kernelnewbies but ended pulling the two other patches)

Best,
Jules