* RE: ARM power-saving measurements
2023-03-31 17:28 ` ARM power-saving measurements Alexander Kozyrev
@ 2023-04-04 2:47 ` Feifei Wang
0 siblings, 0 replies; 2+ messages in thread
From: Feifei Wang @ 2023-04-04 2:47 UTC (permalink / raw)
To: Alexander Kozyrev, Ruifeng Wang; +Cc: dev, nd
Hi, Alex
Thanks for your attention.
Following I will share how to measure the power savings in Arm:
1.Test Setup:
1.1 ensure the dpdk version has been applied the wfe patch:
http://patches.dpdk.org/project/dpdk/cover/20230220085109.3463640-1-feifei.wang2@arm.com/
This is due to dpdk cannot support l3fwd-power 'power monitor' in arm before this patch
1.2 enable wfe instructions in arm:
dpdk/config/arm/meson.build:
'RTE_ARM_USE_WFE', false -> 'RTE_ARM_USE_WFE', true
1.3 build l3fwd-power
meson -Dexamples=l3fwd-power build && cd build && ninja
2. Test Command:
L3fwd-power uses 'power monitor' mode
sudo ./examples/dpdk-l3fwd-power -l 14-15 -n 4 -a 0000:13:00.0 -a 0000:13:00.1 -- -p 0x3 -P --config='(0,0,14),(1,0,15)' --pmd-mgmt=monitor
note: power monitor can just support more than 1 cores.
3. Power saving count:
For arm, wfe instructions can let CPU go into sleeping mode if it is always idle.
Thus, we have 2 ways to collect power saving info.
3.1 Using perf to record dynamic instruction number within 1 second:
$sudo perf stat -C <cpu id>, and then we can get CPU instructions number during a fixed time slot.
For examples:
Performance counter stats for 'CPU(s) 14':
3,506.56 msec cpu-clock # 1.000 CPUs utilized
0 context-switches # 0.000 K/sec
0 cpu-migrations # 0.000 K/sec
0 page-faults # 0.000 K/sec
8,768,815,778 cycles # 2.501 GHz
26,071,802 instructions # 0.00 insn per cycle
<not supported> branches
104,982 branch-misses
3.506978873 seconds time elapsed
Dynamic instructions number for 1 second = 26,071,802/3.506978873
If we disable wfe in arm, we can find 'dynamic instructions number for 1 second'
increases significantly. This also means CPU is running at full load.
3.2 Get CPU power form BMC:
For ampere altra and thunderx2 server, we can look up CPU timely power from BMC.
For example, when we run l3fwd-power in thunderx2, server information->power->consumption:
-----------------------------------------------------------------------------------
CPU0 Current Power Consumption 69 W | 235 BTU/hr
CPU1 Current Power Consumption 0 W | 0 BTU/hr
CPU Power Limit Management Activated
CPU Power Limit in Watts(1-150)
-----------------------------------------------------------------------------------
If we disable wfe, CPU0 Current Power Consumption will increase, then we can know how much power we can save.
Best Regards
Feifei
> -----Original Message-----
> From: Alexander Kozyrev <akozyrev@nvidia.com>
> Sent: Saturday, April 1, 2023 1:29 AM
> To: Feifei Wang <Feifei.Wang2@arm.com>; Ruifeng Wang
> <Ruifeng.Wang@arm.com>
> Cc: dev@dpdk.org
> Subject: RE: ARM power-saving measurements
>
> Hi Feifei/Ruifeng, any advice on power saving measurements on ARM?
>
> Regards,
> Alex
>
> > -----Original Message-----
> > From: Alexander Kozyrev
> > Sent: March 13, 2023 18:08
> > To: Feifei Wang <feifei.wang2@arm.com>; ruifeng.wang@arm.com
> > Subject: ARM power-saving measurements
> >
> > Hi Feifei/ Ruifeng, I can see that power management support on ARM has
> > been integrated successfully.
> > Could you please share the knowledge on how to measure the power
> > savings on this architecture?
> > What are the tools available there? Unfortunately, turbostat is not
> > supported on ARM. How did you test your feature?
> >
> > Regards,
> > Alex
^ permalink raw reply [flat|nested] 2+ messages in thread