Massive power regression going 3.4->3.5

[bwidawsk]

On 2012-08-01 03:06, Chris Wilson wrote:
> On Wed, 01 Aug 2012 10:38:36 +0100, James Bottomley
> <James.Bottomley at HansenPartnership.com> 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,
>>
>> OK, what is trace-cmd?  It looks similar to perf tools ... is that 
>> it?
>
> Yes, it is roughly equivalent and you should be able to achieve the 
> same
> with perf trace - except I haven't done it before so I don't have 
> quick
> advice on how to drive it. :)
> -Chris

Should be something like:
perf record -f -g -e i915:* -a