Am 30.04.2018 um 16:32 schrieb Andrey Grodzovsky: > > > On 04/30/2018 08:08 AM, Christian König wrote: >> Hi Eric, >> >> sorry for the late response, was on vacation last week. >> >> Am 26.04.2018 um 02:01 schrieb Eric W. Biederman: >>> Andrey Grodzovsky <Andrey.Grodzovsky at amd.com> writes: >>> >>>> On 04/25/2018 01:17 PM, Oleg Nesterov wrote: >>>>> On 04/25, Andrey Grodzovsky wrote: >>>>>> here (drm_sched_entity_fini) is also a bad idea, but we still >>>>>> want to be >>>>>> able to exit immediately >>>>>> and not wait for GPU jobs completion when the reason for reaching >>>>>> this code >>>>>> is because of KILL >>>>>> signal to the user process who opened the device file. >>>>> Can you hook f_op->flush method? >> >> THANKS! That sounds like a really good idea to me and we haven't >> investigated into that direction yet. >> >>>> But this one is called for each task releasing a reference to the >>>> the file, so >>>> not sure I see how this solves the problem. >>> The big question is why do you need to wait during the final closing a >>> file? >> >> As always it's because of historical reasons. Initially user space >> pushed commands directly to a hardware queue and when a processes >> finished we didn't need to wait for anything. >> >> Then the GPU scheduler was introduced which delayed pushing the jobs >> to the hardware queue to a later point in time. >> >> This wait was then added to maintain backward compability and not >> break userspace (but see below). >> >>> The wait can be terminated so the wait does not appear to be simply a >>> matter of correctness. >> >> Well when the process is killed we don't care about correctness any >> more, we just want to get rid of it as quickly as possible (OOM >> situation etc...). >> >> But it is perfectly possible that a process submits some render >> commands and then calls exit() or terminates because of a SIGTERM, >> SIGINT etc.. In this case we need to wait here to make sure that all >> rendering is pushed to the hardware because the scheduler might need >> resources/settings from the file descriptor. >> >> For example if you just remove that wait you could close firefox and >> get garbage on the screen for a millisecond because the remaining >> rendering commands where not executed. >> >> So what we essentially need is to distinct between a SIGKILL (which >> means stop processing as soon as possible) and any other reason >> because then we don't want to annoy the user with garbage on the >> screen (even if it's just for a few milliseconds). >> >> Constructive ideas how to handle this would be very welcome, cause I >> completely agree that what we have at the moment by checking >> PF_SIGNAL is just a very very hacky workaround. > > What about changing PF_SIGNALED to PF_EXITING in > drm_sched_entity_do_release > > -      if ((current->flags & PF_SIGNALED) && current->exit_code == > SIGKILL) > +     if ((current->flags & PF_EXITING) && current->exit_code == > SIGKILL) > > From looking into do_exit and it's callers , current->exit_code will > get assign the signal which was delivered to the task. If SIGINT was > sent then it's SIGINT, if SIGKILL then SIGKILL. That's at least a band aid to stop us from abusing PF_SIGNALED. But additional to that change, can you investigate when f_ops->flush() is called when the process exists normally, because of SIGKILL or because of some other signal? Could be that this is more closely to what we are searching for, Christian. > > Andrey > > >> >> Thanks, >> Christian. > > >> >>> >>> Eric >>> _______________________________________________ >>> amd-gfx mailing list >>> amd-gfx at lists.freedesktop.org >>> https://lists.freedesktop.org/mailman/listinfo/amd-gfx >> > > _______________________________________________ > amd-gfx mailing list > amd-gfx at lists.freedesktop.org > https://lists.freedesktop.org/mailman/listinfo/amd-gfx
