On Tue, Oct 01, 2013 at 03:04:01PM -0700, Jesse Barnes wrote: > On Wed, 25 Sep 2013 17:34:57 +0100 > Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> wrote: > > > After applying wait-boost we often find ourselves stuck at higher clocks > > than required. The current threshold value requires the GPU to be > > continuously and completely idle for 313ms before it is dropped by one > > bin. Conversely, we require the GPU to be busy for an average of 90% over > > a 84ms period before we upclock. So the current thresholds almost never > > downclock the GPU, and respond very slowly to sudden demands for more > > power. It is easy to observe that we currently lock into the wrong bin > > and both underperform in benchmarks and consume more power than optimal > > (just by repeating the task and measuring the different results). > > > > An alternative approach, as discussed in the bspec, is to use a > > continuous threshold for upclocking, and an average value for downclocking. > > This is good for quickly detecting and reacting to state changes within a > > frame, however it fails with the common throttling method of waiting > > upon the outstanding frame - at least it is difficult to choose a > > threshold that works well at 15,000fps and at 60fps. So continue to use > > average busy/idle loads to determine frequency change. > > > > v2: Use 3 power zones to keep frequencies low in steady-state mostly > > idle (e.g. scrolling, interactive 2D drawing), and frequencies high > > for demanding games. In between those end-states, we use a > > fast-reclocking algorithm to converge more quickly on the desired bin. > > > > v3: Bug fixes - make sure we reset adj after switching power zones. > > > > v4: Tune - drop the continuous busy thresholds as it prevents us from > > choosing the right frequency for glxgears style swap benchmarks. Instead > > the goal is to be able to find the right clocks irrespective of the > > wait-boost. > > > > Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> > > Cc: Kenneth Graunke <kenneth@xxxxxxxxxxxxx> > > Cc: Stéphane Marchesin <stephane.marchesin@xxxxxxxxx> > > Cc: Owen Taylor <otaylor@xxxxxxxxxx> > > Cc: "Meng, Mengmeng" <mengmeng.meng@xxxxxxxxx> > > Cc: "Zhuang, Lena" <lena.zhuang@xxxxxxxxx> > > --- > > It's a little scary to mess with these, but we've gotten some good > numbers so far so I guess it's ok. > > As a follow up, it might be nice to expose the power, balanced, > performance profiles to userspace via sysfs. Since we can't solve this > problem for all users and all needs, we can just punt it out to > userspace. :) > > Reviewed-by: Jesse Barnes <jbarnes@xxxxxxxxxxxxxxxx> All three merged, thanks for patches&review. I've frobbed the first two with tiny style bikesheds: - Dropped the typedef usage for the plain struct drm_i915_private in new code. - Dropped the extern qualifier for the function prototypes in header files. Cheers, Daniel -- Daniel Vetter Software Engineer, Intel Corporation +41 (0) 79 365 57 48 - http://blog.ffwll.ch _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/intel-gfx
