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. Andrey > > Thanks, > Christian. > >> >> Eric >> _______________________________________________ >> amd-gfx mailing list >> amd-gfx at lists.freedesktop.org >> https://lists.freedesktop.org/mailman/listinfo/amd-gfx >
