On Wed, Aug 21, 2013 at 03:14:22PM +0200, Daniel Vetter wrote: > On Tue, Aug 20, 2013 at 10:17 PM, Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> wrote: > > The first goal is to be able to measure GPU (and invidual ring) busyness > > without having to poll registers from userspace. (Which not only incurs > > holding the forcewake lock indefinitely, perturbing the system, but also > > runs the risk of hanging the machine.) As an alternative we can use the > > perf event counter interface to sample the ring registers periodically > > and send those results to userspace. > > > > To be able to do so, we need to export the two symbols from > > kernel/events/core.c to register and unregister a PMU device. > > > > Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> > > Make sense imo to move the perf gathering into the kernel, a few > random (and rather uninformed) points I've thought of: > - What about the instdone busy bits intel_gpu_top currently presents? I'm contemplating adding 64 u64 (and the rest!), and converting intel_gpu_top as my next use case. > - Shouldn't we have one polling hrtimer that checks all enabled pmu event bits? I had already done so. > - Plans for integrating the various status/debug bits in the display > block (like fetches, fbc compression stuff, ...)? I know that this > will tickle the all-encompassing paranoia about releasing performance > counter details, but we can still hope. Iirc there's also some very > minimal perf counter stuff on the GT arbiter. I'd been adding things as I use them. If we have other counters, yes they will be useful and I strongly advise people working on power/performance sensitive areas start thinking about how we can monitor them in real time.. > Overall I think this is great and should fill the gap until we're > allowed to release some more of the integrated global perf counters > (and even then those should neatly fit in ...). > > For testing I think just running your overlay tool with all possible > events should be good enough (in some headless mode ofc) - functional > testing of perf counter is imo too much fuss. My aim is to have complete integration with perf as well as having a pretty tool for my own use. (It has already shown me more bugs than I thought existed...) -Chris -- Chris Wilson, Intel Open Source Technology Centre _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/intel-gfx
