On Tue, 22 May 2012 17:14:11 +0100 Joe Bloggsian <joebloggsian at gmail.com> wrote: > Thanks for the help, I've had time to build and test a few kernels on > various systems following your advice. > > In summary I need both a new drm-intel-next kernel from Daniel's tree *and* > the patch you suggest to get expected GPU turbo behaviour, compared to a > stable 3.2 kernel. > > Test results from Core i7 3770 / HD4000: With just the latest drm-intel-next > kernel (commit 98b6bd), the symptoms are as before, max GPU turbo of 600MHz > in the test app. With just the (equivalent of the) patch applied to a > 3.2.18 kernel, the max turbo is better (>600) but still often less than > expected. With both patch and kernel, the GPU immediately spins up to > 1.15GHz and stays there, as expected - and the measured test app > performance is nearly twice what I get with the up to date Ubuntu 12.04 x64 > kernel! Awesome, thanks so much for testing, I'll send the patch upstream now. > I've also seen the full turbo kick in for other media workloads with the > default kernel, but one way of reliably reproducing this problem for me is > to run the avcenc test app that is part of libva. > > The same problem exists on Sandy Bridge. Although the turbo and performance > gaps between the latest released Ubuntu 12.04 kernel and the patched 3.4 > kernel are less than Ivy Bridge, they are still significant on my core i3 > 2310M / HD3000 laptop. Ok good to know; the patch will apply to SNB too, the fact you tested things there makes my life easier. :) -- Jesse Barnes, Intel Open Source Technology Center
