Yeah, it was just spelling typos. I'll add your RB to it and repost. I cannot push to drm-misc-next, but hope someone will pick it up. Regards, Luben On 2022-10-24 14:42, Christian König wrote: > I've seen that one, but couldn't figure out what was actually changed > between the two. > > If you just fixed a typo feel free to add my R-B to this one as well. > > Christian. > > Am 24.10.22 um 19:25 schrieb Luben Tuikov: >> Hi Christian, >> >> Can you add an R-B to V1 of this patch, as the v1 is what I'd like pushed. >> I sent it right after this one. >> >> Regards, >> Luben >> >> On 2022-10-24 06:42, Christian König wrote: >>> Am 22.10.22 um 03:09 schrieb Luben Tuikov: >>>> The currently default Round-Robin GPU scheduling can result in starvation >>>> of entities which have a large number of jobs, over entities which have >>>> a very small number of jobs (single digit). >>>> >>>> This can be illustrated in the following diagram, where jobs are >>>> alphabetized to show their chronological order of arrival, where job A is >>>> the oldest, B is the second oldest, and so on, to J, the most recent job to >>>> arrive. >>>> >>>> ---> entities >>>> j | H-F-----A--E--I-- >>>> o | --G-----B-----J-- >>>> b | --------C-------- >>>> s\/ --------D-------- >>>> >>>> WLOG, asuming all jobs are "ready", then a R-R scheduling will execute them >>>> in the following order (a slice off of the top of the entities' list), >>>> >>>> H, F, A, E, I, G, B, J, C, D. >>>> >>>> However, to mitigate job starvation, we'd rather execute C and D before E, >>>> and so on, given, of course, that they're all ready to be executed. >>>> >>>> So, if all jobs are ready at this instant, the order of execution for this >>>> and the next 9 instances of picking the next job to execute, should really >>>> be, >>>> >>>> A, B, C, D, E, F, G, H, I, J, >>>> >>>> which is their chronological order. The only reason for this order to be >>>> broken, is if an older job is not yet ready, but a younger job is ready, at >>>> an instant of picking a new job to execute. For instance if job C wasn't >>>> ready at time 2, but job D was ready, then we'd pick job D, like this: >>>> >>>> 0 +1 +2 ... >>>> A, B, D, ... >>>> >>>> And from then on, C would be preferred before all other jobs, if it is ready >>>> at the time when a new job for execution is picked. So, if C became ready >>>> two steps later, the execution order would look like this: >>>> >>>> ......0 +1 +2 ... >>>> A, B, D, E, C, F, G, H, I, J >>>> >>>> This is what the FIFO GPU scheduling algorithm achieves. It uses a >>>> Red-Black tree to keep jobs sorted in chronological order, where picking >>>> the oldest job is O(1) (we use the "cached" structure), and balancing the >>>> tree is O(log n). IOW, it picks the *oldest ready* job to execute now. >>>> >>>> The implemntation is already in the kernel, and this commit only changes >>>> the default GPU scheduling algorithm to use. >>>> >>>> This was tested and achieves about 1% faster performance over the Round >>>> Robin algorithm. >>>> >>>> Cc: Christian König <christian.koenig@xxxxxxx> >>>> Cc: Alex Deucher <Alexander.Deucher@xxxxxxx> >>>> Cc: Direct Rendering Infrastructure - Development <dri-devel@xxxxxxxxxxxxxxxxxxxxx> >>>> Signed-off-by: Luben Tuikov <luben.tuikov@xxxxxxx> >>> Reviewed-by: Christian König <christian.koenig@xxxxxxx> >>> >>>> --- >>>> drivers/gpu/drm/scheduler/sched_main.c | 4 ++-- >>>> 1 file changed, 2 insertions(+), 2 deletions(-) >>>> >>>> diff --git a/drivers/gpu/drm/scheduler/sched_main.c b/drivers/gpu/drm/scheduler/sched_main.c >>>> index 2fab218d708279..d0ff9e11cb69fa 100644 >>>> --- a/drivers/gpu/drm/scheduler/sched_main.c >>>> +++ b/drivers/gpu/drm/scheduler/sched_main.c >>>> @@ -62,13 +62,13 @@ >>>> #define to_drm_sched_job(sched_job) \ >>>> container_of((sched_job), struct drm_sched_job, queue_node) >>>> >>>> -int drm_sched_policy = DRM_SCHED_POLICY_RR; >>>> +int drm_sched_policy = DRM_SCHED_POLICY_FIFO; >>>> >>>> /** >>>> * DOC: sched_policy (int) >>>> * Used to override default entities scheduling policy in a run queue. >>>> */ >>>> -MODULE_PARM_DESC(sched_policy, "Specify schedule policy for entities on a runqueue, " __stringify(DRM_SCHED_POLICY_RR) " = Round Robin (default), " __stringify(DRM_SCHED_POLICY_FIFO) " = use FIFO."); >>>> +MODULE_PARM_DESC(sched_policy, "Specify the scheduling policy for entities on a run-queue, " __stringify(DRM_SCHED_POLICY_RR) " = Round Robin, " __stringify(DRM_SCHED_POLICY_FIFO) " = FIFO (default)."); >>>> module_param_named(sched_policy, drm_sched_policy, int, 0444); >>>> >>>> static __always_inline bool drm_sched_entity_compare_before(struct rb_node *a, >>>> >>>> base-commit: 16d2a3f2ad1d2b95bf9122c910c63b0efe74179d >
