Am 18.01.19 um 16:21 schrieb Grodzovsky, Andrey: > > On 01/18/2019 04:25 AM, Koenig, Christian wrote: >> [SNIP] >>>>>> Re-arming the timeout should probably have a much reduced value >>>>>> when the job hasn't changed. E.g. something like a few ms. >>> Now i got thinking about non hanged job in progress (job A) and let's >>> say it's a long job , it just started executing but due to time out of >>> another job (job B) on another (or this scheduler) it's parent cb got >>> disconnected, we disarmed the tdr timer for the job's scheduler, >>> meanwhile the timed out job did manage to complete before HW reset >>> check and hence we skip HW reset, attach back the cb and rearm job's A >>> tdr timer with a future value of few ms only - aren't we going to get >>> false tdr triggered on job B now because we didn't let it enough time >>> to run and complete ? I would prefer the other extreme of longer time >>> for time out to trigger then false TDR. Optimally we would have per >>> job timer and rearm to exactly the reminder of it's time out value - >>> but we gave up on per job tdr work long ago. >> Well we only re-arm the timeout with a shorter period if it already >> triggered once. If we just suspend the timeout then we should still use >> the longer period. > Can you explain more on this ? I don't get it. See drm_sched_job_timedout(), we re-arm the timeout at the end of the procedure. We should change that and re-arm the timer with a much lower timeout if the job is still not finished. Christian. > > Andrey > >>> In general the more i think about it (correct me if I am wrong) I am >>> less sure how much the optimization feature is useful - if job's time >>> out did trigger what are the chances that the little more time we give >>> it between beginning of tdr function and the time we do start the >>> actual HW reset will be exactly what it needed to complete. Also, this >>> is still not water proof as the job might complete and signal it's HW >>> fence exactly after we checked for completion but before starting the >>> HW reset code. >> I don't see this as an optimization, but rather as mandatory for correct >> operation. >> >> See without this we can run into issues because we execute jobs multiple >> times. That can still happen with this clean handling, but it is much >> more unlikely. >> >> Christian. >> >>> Andrey >>> >>>>> By unchanged you mean when we didn't resubmit the job because of the >>>>> optimized non HW reset, right ? >>>> Correct, yes. >>>> >>>>>>> About flushing tdr jobs in progress from .free_job cb - looks like >>>>>>> drm_sched_job_finish->cancel_delayed_work_sync is not enough, we >>>>>>> still need to take care of flushing all sced->work_tdr for a >>>>>>> device and for all devices in hive for XGMI. >>>>>>> What do you think ? >>>>>> Why should that be necessary? We only wait for the delayed work to >>>>>> make sure that the job is not destroyed while dealing with it. >>>>>> >>>>>> Christian. >>>>> But we might not be waiting for the correct sched->work_tdr, we do >>>>> the reset routine for all schedulers in a device accessing their >>>>> jobs too and not only for the scheduler to which the job belongs. >>>>> For XGMI not only that, we reset all the devices in the hive. >>>> That is harmless you only need to wait for the work_tdr of the >>>> current scheduler, not for all of them. >>>> >>>>> I was thinking, amdgpu driver is not even interested in allowing >>>>> multiple sced->tdr to execute together - we have to serialize all of >>>>> them anyway with the trylock mutex (even without XGMI), v3d in >>>>> v3d_job_timedout seems also to reset all of his schedulers from the >>>>> tdr work. Would it make sense to provide the sched->work_td as init >>>>> parameter to scheduler (same one for all schedulers) so we can >>>>> enforce serialization by disallowing more then 1 tdr work to execute >>>>> in the same time ? Other drivers interested to do in parallel can >>>>> provide unique sched->work_tdr per scheduler. This does imply >>>>> drm_sched_job_timedout has to removed and delegated to specific >>>>> driver implementation as probably other code dealing with >>>>> sched->work_tdr... Maybe even move tdr handling to the driver all >>>>> together ? >>>> Yeah, I was thinking something similar. The problem with this >>>> approach is that a delayed work item can have only one delay, but for >>>> multiple engines we need multiple delays. >>>> >>>> What we could do is to make it a timer instead and raise the work >>>> item from the device specific callback. >>>> >>>> But that doesn't really saves us the stop all schedulers trouble, so >>>> it doesn't buy us much in the end if I see this correctly. >>>> >>>> Christian. >> _______________________________________________ >> amd-gfx mailing list >> amd-gfx@xxxxxxxxxxxxxxxxxxxxx >> https://lists.freedesktop.org/mailman/listinfo/amd-gfx _______________________________________________ amd-gfx mailing list amd-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/amd-gfx
