Op 04-09-13 05:21, Ben Skeggs schreef: > On Tue, Sep 3, 2013 at 12:31 AM, Maarten Lankhorst > <maarten.lankhorst@xxxxxxxxxxxxx> wrote: >> This increases the chance slightly that recovery from lockup can happen >> succesfully. > I'd *really* love to see proof of this. When channels die, all > outstanding fences are marked as signalled. This should do absolutely > nothing... nv84+ heavily rely on fences though, and a race like this is possible: - channel 0 uses a bo from channel 1, queues a wait somewhere in the command stream for it. - channel 1 dies cleanly, but userspace creates a new channel in its place, fence counter is reset to 0. - channel 0 reaches the NV84_SUBCHAN_SEMAPHORE_TRIGGER.ACQUIRE_GEQUAL op, waits on fence in channel 1 to signal forever. Channel 0 could be the global drm channel used for buffer moves, which would result in a hang. This may seem unlikely, but I believe that parallel piglit runs could trigger it. If not, simply creating an operation that takes a few seconds in channel 0 and then queuing a command that uses a bo from channel 1 while chan1 is still busy, then deleting/recreating chan1 could trigger it. ~Maarten _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/dri-devel
