Massive power regression going 3.4->3.5

[Daniel Vetter]

On Wed, Aug 01, 2012 at 11:08:19AM +0100, James Bottomley wrote:
> On Wed, 2012-08-01 at 09:58 +0100, Chris Wilson wrote:
> > On Wed, 01 Aug 2012 09:45:04 +0100, James Bottomley <James.Bottomley at HansenPartnership.com> wrote:
> > > On Wed, 2012-08-01 at 09:16 +0100, Chris Wilson wrote:
> > > > On Wed, 01 Aug 2012 09:06:12 +0100, James Bottomley <James.Bottomley at HansenPartnership.com> wrote:
> > > > > I got the attached to apply and it doesn't really improve the idle power
> > > > > much (12.5W).
> > > > 
> > > > That's good to know. Next step is to try overriding i915.semaphores.
> > > > Can you please test with i915.semaphores=0 and i915.semaphores=1?
> > > 
> > > There's not much point doing i915_semaphores=1 since that's the default
> > > on gen 6 hardware, but i915_semaphores=0 recovers and idle power of
> > > ~6.5W
> > 
> > It is only the default if iommu is off, and changing the default
> > was one of the side-effects of the patch you bisected.
> > 
> > Can you please login to the desktop, let it idle, record
> > /sys/kernel/debug/dri/0/i915_cur_delayinfo and .../i915_drpc_info.
> > Then trace-cmd record -e i915 sleep 10s, and follow up with a new pair
> > of /sys/kernel/debug/dri/0/i915_cur_delayinfo and .../i915_drpc_info.
> > 
> > This will let us see whether the pm counters are truly advancing and
> > what activity the driver is performing whilst idle.
> 
> OK, so here it is
> 
> James

Hm, if I haven't botched the math, you have a rc6 residency of about 320
seconds between the two cats of drpc_info. Can you please script this so
that we have exactly 10s in between? (Aside: 3.6 has a neat interface for
rc6 residency in sysfs ...)

Also, you need to attach the output of trace-cmd report (like with perf),
so that we see the tracepoints in detail.

Another quick thing to confirm: What is the power consumption on the old
kernel when booting with i915.i915_semaphores=1?

Thanks, Daniel
-- 
Daniel Vetter
Mail: daniel at ffwll.ch
Mobile: +41 (0)79 365 57 48