On Fri, 27 Oct 2023 09:35:01 +0200 Christian König <christian.koenig@xxxxxxx> wrote:Am 27.10.23 um 09:32 schrieb Boris Brezillon:On Fri, 27 Oct 2023 09:22:12 +0200 Christian König <christian.koenig@xxxxxxx> wrote:+ + /** + * @update_job_credits: Called once the scheduler is considering this + * job for execution. + * + * Drivers may use this to update the job's submission credits, which is + * useful to e.g. deduct the number of native fences which have been + * signaled meanwhile. + * + * The callback must either return the new number of submission credits + * for the given job, or zero if no update is required. + * + * This callback is optional. + */ + u32 (*update_job_credits)(struct drm_sched_job *sched_job);Why do we need an extra callback for this? Just document that prepare_job() is allowed to reduce the number of credits the job might need.->prepare_job() is called only once if the returned fence is NULL, but we need this credit-update to happen every time a job is considered for execution by the scheduler.But the job is only considered for execution once. How do you see that this is called multiple times?Nope, it's not. If drm_sched_can_queue() returns false, the scheduler will go look for another entity that has a job ready for execution, and get back to this entity later, and test drm_sched_can_queue() again. Basically, any time drm_sched_can_queue() is called, the job credits update should happen, so we have an accurate view of how many credits this job needs.
Well, that is the handling which I already rejected because it creates unfairness between processes. When you consider the credits needed *before* scheduling jobs with a lower credit count are always preferred over jobs with a higher credit count.
What you can do is to look at the credits of a job *after* it was picked up for scheduling so that you can scheduler more jobs.
Regards,
Christian.
