Messages in this thread | | | Date | Thu, 27 Oct 2022 10:19:19 +0200 | Subject | Re: [PATCH] drm/scheduler: set current_entity to next when remove from rq | From | Christian König <> |
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Am 27.10.22 um 10:07 schrieb Luben Tuikov: > On 2022-10-27 03:01, Luben Tuikov wrote: >> On 2022-10-25 13:50, Luben Tuikov wrote: >>> Looking... >>> >>> Regards, >>> Luben >>> >>> On 2022-10-25 09:35, Alex Deucher wrote: >>>> + Luben >>>> >>>> On Tue, Oct 25, 2022 at 2:55 AM brolerliew <brolerliew@gmail.com> wrote: >>>>> When entity move from one rq to another, current_entity will be set to NULL >>>>> if it is the moving entity. This make entities close to rq head got >>>>> selected more frequently, especially when doing load balance between >>>>> multiple drm_gpu_scheduler. >>>>> >>>>> Make current_entity to next when removing from rq. >>>>> >>>>> Signed-off-by: brolerliew <brolerliew@gmail.com> >>>>> --- >>>>> drivers/gpu/drm/scheduler/sched_main.c | 5 +++-- >>>>> 1 file changed, 3 insertions(+), 2 deletions(-) >>>>> >>>>> diff --git a/drivers/gpu/drm/scheduler/sched_main.c b/drivers/gpu/drm/scheduler/sched_main.c >>>>> index 2fab218d7082..00b22cc50f08 100644 >>>>> --- a/drivers/gpu/drm/scheduler/sched_main.c >>>>> +++ b/drivers/gpu/drm/scheduler/sched_main.c >>>>> @@ -168,10 +168,11 @@ void drm_sched_rq_remove_entity(struct drm_sched_rq *rq, >>>>> spin_lock(&rq->lock); >>>>> >>>>> atomic_dec(rq->sched->score); >>>>> - list_del_init(&entity->list); >>>>> >>>>> if (rq->current_entity == entity) >>>>> - rq->current_entity = NULL; >>>>> + rq->current_entity = list_next_entry(entity, list); >>>>> + >>>>> + list_del_init(&entity->list); >>>>> >>>>> if (drm_sched_policy == DRM_SCHED_POLICY_FIFO) >>>>> drm_sched_rq_remove_fifo_locked(entity); >>>>> -- >>>>> 2.34.1 >>>>> >> Looks good. I'll pick it up into some other changes I've in tow, and repost >> along with my changes, as they're somewhat related. > Actually, the more I look at it, the more I think that we do want to set > rq->current_entity to NULL in that function, in order to pick the next best entity > (or scheduler for that matter), the next time around. See sched_entity.c, > and drm_sched_rq_select_entity() where we start evaluating from the _next_ > entity. > > So, it is best to leave it to set it to NULL, for now.
Apart from that this patch here could cause a crash when the entity is the last one in the list.
In this case current current_entity would be set to an incorrect upcast of the head of the list.
Regards, Christian.
> > Regards, > Luben >
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