On Fri, Nov 18, 2016 at 4:48 AM, Daniel Vetter <daniel@xxxxxxxx> wrote: > On Fri, Nov 18, 2016 at 10:42:07AM +0100, Daniel Vetter wrote: >> On Thu, Nov 17, 2016 at 08:40:10PM -0600, Bjorn Helgaas wrote: >> > On Fri, Nov 18, 2016 at 10:42:20AM +0900, Michel Dänzer wrote: >> > > On 18/11/16 08:48 AM, Bjorn Helgaas wrote: >> > > > >> > > > Popping the stack all the way back to Emil's Nov 8 message: >> > > > >> > > > When using the Mesa drivers alongside firefox [1] (since Mesa 13.0), >> > > > glxinfo (Mesa 10.0) and others, all the GPUs* will be awaken, >> > > > causing unwanted delays and increased power usage. >> > > > >> > > > [1] https://bugs.freedesktop.org/show_bug.cgi?id=98502 >> > > > >> > > > The bug is about a delay in starting firefox, thunderbird, or >> > > > chromium. I assume the browser starts on the current, powered-up, >> > > > GPU. I don't understand why we care about the revision of other, >> > > > powered-off, GPUs. >> > > >> > > We don't. The problem is that the current libdrm API unconditionally >> > > provides the revision. The plan is to address this in two ways: >> > > >> > > * Add new libdrm API which allows the caller to say "I don't need the >> > > revision", and make Mesa use that. Users having those changes will not >> > > run into the problem even on older kernels. >> > > >> > > * Add the separate revision file in sysfs and make libdrm use that for >> > > its current API. This means that even callers of the current libdrm API >> > > will not run into the problem with newer kernels. >> > >> > Why do we care about *anything* for the other, powered-off, GPUs? >> > Even users of the new libdrm API who say "I don't need the revision" >> > are still getting the vendor/device/etc for those other GPUs. >> >> egl device enumeration, and for that you need to know what gpus you have >> and load their drivers. Afaik. Yes by default they'll all select the >> online gpu, but they can opt for the faster/other one on multi-gpu >> machines. > > Now the only reason we can avoid parsing the revision flag is that most > drivers don't care, and the one that does (i915) is generally the one > that's on and only needs it after driver init. But fundamentally we can't > avoid the enumeration, and imo it's better to cache this in the kernel > than implement some userspace thingy (require udev or whatever). > We need the revision id as well. Alex > I guess in the end I don't really get why caching the revision in the > kernel is a problem ... > -Daniel > -- > Daniel Vetter > Software Engineer, Intel Corporation > http://blog.ffwll.ch > _______________________________________________ > dri-devel mailing list > dri-devel@xxxxxxxxxxxxxxxxxxxxx > https://lists.freedesktop.org/mailman/listinfo/dri-devel -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
