On Wed, Nov 16, 2011 at 16:59, Andrew Lutomirski <andy at luto.us> wrote: > > On Nov 16, 2011 7:54 AM, "Daniel Vetter" <daniel.vetter at ffwll.ch> wrote: >> >> On Mon, Nov 14, 2011 at 21:39, Eugeni Dodonov <eugeni.dodonov at intel.com> >> wrote: >> > Most of the rc6-related hangs and major issues were addressed for the >> > past >> > months. >> > >> > Let's re-enable it by default to provide a more wider testing, and catch >> > the remaining problems. >> > >> > According to tests, enablement of rc6 results in up to +50% improvements >> > in power usage and battery life, so it certainly would be a nice feature >> > to have enabled by default. >> > >> > Also, most of the issues related to rc6 seem to came from VTd, so if you >> > are experiencing any problems with it, try disabling VTd in bios or >> > using >> > intel_iommu=off kernel parameter to investigate whether it solves the >> > issue. >> > >> > Acked-by: Keith Packard <keithp at keithp.com> >> > CC: Daniel Vetter <daniel.vetter at ffwll.ch> >> > CC: Jesse Barnes <jbarnes at virtuousgeek.org> >> > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=38567 >> > Signed-off-by: Eugeni Dodonov <eugeni.dodonov at intel.com> >> >> Iirc the same applies to rc6 as to semaphores. We have bug reports >> that it causes hard-hangs in combination with DMAR. I haven't yet >> gotten around to poking the relevant reporters whether ppgtt changes >> anything, because internet access here at the Intel Poland site sucks. >> So again I think we need to disable this on snb when DMAR is on. > > I can reproduce the semaphore hang easily.? Where are the ppgtt > patches/settings to play with? > > FWIW, rc6 is a *huge* win on my SNB laptop, and the laptop has always been > rock-solid with any set of options.? Maybe this is only an issue on desktop > parts, and the 5W difference is a bigger deal on laptops anyway. Grab the ppgtt branch from my fdo repo: http://cgit.freedesktop.org/~danvet/drm/ Note that this branch will only work on snb/ivb and that resume is broken. Also, after the first gpu reset ppgtt will get disabled and hence your machine might die rather quickly. So perhaps boot with i915.reset=0 to prevent that. Testing feedback highly welcome. Yours, Daniel -- Daniel Vetter daniel.vetter at ffwll.ch - +41 (0) 79 365 57 48 - http://blog.ffwll.ch
