topic Re: Intel Xeon Platinum 8176 Max Frequency in Mobile and Desktop Processors

Intel Xeon Platinum 8176 Max Frequency

CCair1 — Thu, 12 Sep 2019 17:44:24 GMT

Hello,

I'm running on a HPC cluster with blades running dual Intel Xeon Platinum 8176.

The specs say that the base frequency is 2.1 GHz, but the max frequency should be up to 3.8 GHz when running on a single core, and somewhere less when running on more cores (see here)

However when I use the command lscpu I get the following:

# lscpu

Architecture: x86_64

CPU op-mode(s): 32-bit, 64-bit

Byte Order: Little Endian

CPU(s): 112

On-line CPU(s) list: 0-111

Thread(s) per core: 2

Core(s) per socket: 28

Socket(s): 2

NUMA node(s): 2

Vendor ID: GenuineIntel

CPU family: 6

Model: 85

Model name: Intel(R) Xeon(R) Platinum 8176 CPU @ 2.10GHz

Stepping: 4

CPU MHz: 2101.000

CPU max MHz: 2101.0000

CPU min MHz: 1000.0000

BogoMIPS: 4200.00

Virtualization: VT-x

L1d cache: 32K

L1i cache: 32K

L2 cache: 1024K

L3 cache: 39424K

NUMA node0 CPU(s): 0-27,56-83

NUMA node1 CPU(s): 28-55,84-111

This seems to suggest that the TurboBoost is not enable in the BIOS, but when I run cpupower frequency-info it seems to say it actually is:

# cpupower frequency-info

analyzing CPU 0:

driver: acpi-cpufreq

CPUs which run at the same hardware frequency: 0

CPUs which need to have their frequency coordinated by software: 0

maximum transition latency: 10.0 us

hardware limits: 1000 MHz - 2.10 GHz

available frequency steps: 2.10 GHz, 2.10 GHz, 2.00 GHz, 1.90 GHz, 1.80 GHz, 1.70 GHz, 1.60 GHz, 1.50 GHz, 1.40 GHz, 1.30 GHz, 1.20 GHz, 1.10 GHz, 1000 MHz

available cpufreq governors: conservative userspace powersave ondemand performance

current policy: frequency should be within 1000 MHz and 2.10 GHz.

The governor "ondemand" may decide which speed to use

within this range.

current CPU frequency: Unable to call hardware

current CPU frequency: 2.10 GHz (asserted by call to kernel)

boost state support:

Supported: yes

Active: yes

What else could be limiting the max frequency to the base frequency?

Thanks,

Claudio

Re: Intel Xeon Platinum 8176 Max Frequency

n_scott_pearson — Fri, 13 Sep 2019 06:26:10 GMT

It does not suggest that at all; you are making bad assumptions (yes, I am rolling my eyes). This lscpu software is simply showing the range of processor frequencies it could see during its operation. It tells us that it just happens that Turbo Boost was not being used while this tool was running. The cpupower tool is telling you the frequencies that are used for idling down the processor when it is not busy. This also has nothing to do with Turbo Boost either.

...S

Re: Intel Xeon Platinum 8176 Max Frequency

CCair1 — Fri, 13 Sep 2019 14:54:38 GMT

Scott,

when the tool was running a CFD simulation was also running on all 56 cores. the load average was 56 and had been that for a while (i.e. hours). So I expected that the CPU MHz: line in the lscpu output, which to my knowledge show the current cpu frequency to be much more than the 2101.000 value. Isn't that the case?

Since TurboBoost is enable, if it is not running when the CPU is completely loaded, when is it supposed to be running?

Re: Intel Xeon Platinum 8176 Max Frequency

n_scott_pearson — Fri, 13 Sep 2019 23:58:15 GMT

If you are separately running a application that is spread across all available cores, then the Turbo Boost feature will most definitely NOT be active. This feature is specifically used when relatively few cores are active. It is trying to make use of any thermal and power headroom that is available to boost the performance of the few cores that are active. There will simply not be any headroom if all cores are active.

There are a number of apps around that monitors the Turbo Boost feature. There is even one from Intel (Intel Turbo Boost Technology Monitor 3.0). Try running this tool.

...S

Re: Intel Xeon Platinum 8176 Max Frequency

CCair1 — Mon, 16 Sep 2019 16:25:39 GMT

I ended up using turbostat to find the answer I was looking for.

Yes, TurboBoost is enable and IS active.

turbostat confirm the when all cores were busy, they were running around about 2.4-2.5 GHz, which is the results I was excepting since the application running uses AVX2 (See https://en.wikichip.org/wiki/intel/xeon_platinum/8176).

Cheers.