On Tue, Jun 11, 2013 at 1:43 PM, Terje Bergström <tbergstrom@xxxxxxxxxx> wrote: > On 11.06.2013 14:00, Daniel Vetter wrote: >> We don't use the EAGAIN ioctl restarting to resubmit the batchbuffer >> which blew up the gpu (that one has been submitted already in a >> different ioctl call), but to be able to restart the ioctl after the >> reset has completed: We need to kick every thread which is potentially >> holding GEM locks and make sure that we block them (at a point where >> they don't hold any locks) until the reset handler completed. To avoid >> a validation nightmare we use the same codepaths as we use for signal >> interrupts, so ioctl restarting is a very natural fit for this. >> >> Resubmitting victim workloads when a gpu crash happened is something >> the reset handler would do (kernel work item currently), not any >> userspace process doing an ioctl. But atm we don't resubmit victimized >> workloads. > > I don't understand the end-to-end of how resubmit is supposed to work. > User space is not supposed to resubmit, but still EAGAIN is returned to > user space, and drmIoctl() in user space just calls the came ioctl > again. Sounds like drmIoctl() is completely wrong. Maybe it wasn't clear, but -EAGAIN does _not_ resubmit work. -EAGAIN is used to restart the ioctl if we had to kick a thread (to make sure it doesn't hold any locks), e.g. for a blocking wait on oustanding rendering. The codepaths taken work exactly as if the thread is interrupt with a signal. > In Tegra, when a job blows up, we reset the involved units, and set the > pushbuffer pointer of host1x to point to the next job, and re-enable > units. There's no need for anybody to resubmit anything, as kernel > already has them. Yeah, that's how it works in i915.ko, too. -Daniel -- Daniel Vetter Software Engineer, Intel Corporation +41 (0) 79 365 57 48 - http://blog.ffwll.ch -- To unsubscribe from this list: send the line "unsubscribe linux-tegra" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
