Massive power regression going 3.4->3.5

James Bottomley James.Bottomley at HansenPartnership.com
Wed Aug 1 03:08:19 PDT 2012


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

---

jejb at dabdike> cat /sys/kernel/debug/dri/0/i915_cur_delayinfo
GT_PERF_STATUS: 0x000016c7
RPSTAT1: 0x0004160d
Render p-state ratio: 22
Render p-state VID: 199
Render p-state limit: 255
CAGF: 1100MHz
RP CUR UP EI: 96491us
RP CUR UP: 252us
RP PREV UP: 0us
RP CUR DOWN EI: 0us
RP CUR DOWN: 513us
RP PREV DOWN: 0us
Lowest (RPN) frequency: 650MHz
Nominal (RP1) frequency: 650MHz
Max non-overclocked (RP0) frequency: 1100MHz
jejb at dabdike> cat /sys/kernel/debug/dri/0/i915_drpc_info
RC information inaccurate because somebody holds a forcewake reference 
Video Turbo Mode: yes
HW control enabled: yes
SW control enabled: no
RC1e Enabled: no
RC6 Enabled: yes
Deep RC6 Enabled: no
Deepest RC6 Enabled: no
Current RC state: on
Core Power Down: no
RC6 "Locked to RPn" residency since boot: 0
RC6 residency since boot: 360123443
RC6+ residency since boot: 0
RC6++ residency since boot: 0
jejb at dabdike> ./git/trace-cmd/trace-cmd record -e i915 sleep 10s
trace-cmd: Permission denied
  opening '/sys/kernel/debug/tracing/tracing_on'
jejb at dabdike> sudo ./git/trace-cmd/trace-cmd record -e i915 sleep 10s
/sys/kernel/debug/tracing/events/i915/filter
/sys/kernel/debug/tracing/events/*/i915/filter
Kernel buffer statistics:
  Note: "entries" are the entries left in the kernel ring buffer and are not
        recorded in the trace data. They should all be zero.

CPU: 0
entries: 0
overrun: 0
commit overrun: 0
bytes: 1080
oldest event ts:  1076.352744
now ts:  1076.651396

CPU: 1
entries: 0
overrun: 0
commit overrun: 0
bytes: 932
oldest event ts:  1067.676405
now ts:  1076.651452

CPU: 2
entries: 0
overrun: 0
commit overrun: 0
bytes: 3784
oldest event ts:  1076.090225
now ts:  1076.651501

CPU: 3
entries: 0
overrun: 0
commit overrun: 0
bytes: 0
oldest event ts: 15281105439.050279
now ts:  1076.651550

CPU0 data recorded at offset=0x39a000
    221184 bytes in size
CPU1 data recorded at offset=0x3d0000
    16384 bytes in size
CPU2 data recorded at offset=0x3d4000
    32768 bytes in size
CPU3 data recorded at offset=0x3dc000
    0 bytes in size
jejb at dabdike> cat /sys/kernel/debug/dri/0/i915_cur_delayinfo
GT_PERF_STATUS: 0x000016c7
RPSTAT1: 0x0004160d
Render p-state ratio: 22
Render p-state VID: 199
Render p-state limit: 255
CAGF: 1100MHz
RP CUR UP EI: 49171us
RP CUR UP: 122us
RP PREV UP: 0us
RP CUR DOWN EI: 0us
RP CUR DOWN: 562us
RP PREV DOWN: 0us
Lowest (RPN) frequency: 650MHz
Nominal (RP1) frequency: 650MHz
Max non-overclocked (RP0) frequency: 1100MHz
jejb at dabdike> cat /sys/kernel/debug/dri/0/i915_drpc_info
RC information accurate: yes
Video Turbo Mode: yes
HW control enabled: yes
SW control enabled: no
RC1e Enabled: no
RC6 Enabled: yes
Deep RC6 Enabled: no
Deepest RC6 Enabled: no
Current RC state: RC6
Core Power Down: no
RC6 "Locked to RPn" residency since boot: 0
RC6 residency since boot: 362653127
RC6+ residency since boot: 0
RC6++ residency since boot: 0




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