Hi Lucas 2017-09-13 13:01 GMT+02:00 Lucas Stach <l.stach@xxxxxxxxxxxxxx>: > Am Dienstag, den 12.09.2017, 17:11 +0200 schrieb Christian Gmeiner: >> In a perfect world we would be able to read GPU registers of interest >> via the command stream with a 'read-register' command/package. For perf >> counters it is a must to read them synchronized with the GPU to put the >> values in relation to a draw command. As Vivante GPUs do not provide this >> functionality we need to emulate it in software. >> >> >> We need to support three different kind of perf register types: >> >> 1) normal register >> This is the easierst case where we can simply read the register and we >> are done. >> >> 2) debug register >> We need to configure the mux register and then read the debug register value. >> >> 3) pipeline register >> We need to 'iterate' over all pixel pipes and sum up the values. The 'iteration' >> is done by select the pipe of interest via HI_CLOCK_CONTROL_DEBUG_PIXEL_PIPE. >> There is also need to configure the mux register. >> >> >> Allowing the userspace to do it all by its own feels quite error prone and not >> future-proof. Thats why the kernel exports all performance domains and their >> signals to the userspace via two new ioctls. So the kernel knows all performance >> counters and how to sample them. >> >> At the moment all performacne domains and signals get exported to all gpu pipe types, >> but that can be changed in follow-up patches. > > Okay, after testing the V4 patches I'm convinced that we need this > filter _before_ any of this can go in. > Will integrate this in the next version of this series. > At least on GC3000 profiling the PE counters wastes the GPU bad enough > that not even our regular GPU recovery mechanism is able to get it back > to life. This is a trivial DOS vector, which we simply can't allow in > the kernel driver. For this to go in, we need some way to only export > the counters, which are _tested_ to be safe on the hardware. > I have tested all exported counters on a GC2000 with glxgears - one perf counter for each glxgears run. I have not seen any GPU hangs or similar. Will redo this 'testing procedure on a GC3000. Thanks for review :) greets -- Christian Gmeiner, MSc https://christian-gmeiner.info _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
