Low clockspeed on Threadripper 1920X during single threaded workload

[mikat]

Hi everyone,

 

I'm doing research and the machine my university provided is one with a 1920X, I'm now doing performance benchmarking and watching the clock speed of the CPU to see I'm getting good results, in all core (in my case 20/24 threads) workloads it turbos to 3.5-3.7 GHz but running the exact same workload on one or two cores results in the CPU staying at its minimum clock frequency of 2.2 GHz, anyone have any idea why this might be? Normally I'd expect these tasks to turbo the CPU to 3.9 or 4.0 GHz as 4.0 GHz is the advertised boost clock.

 

OS: Ubuntu 20.04.4 LTS x86_64
CPU: AMD Threadripper 1920X

This is my setup for watching clock speeds: 

watch -n 0.2 'lscpu | grep "CPU MHz"'

Every 0,2s: lscpu | grep "CPU MHz"        

CPU MHz:                         2156.756

[Origami Cactus]

Maybe what you are using doesn't adequately report ryzen clock speeds. When single core load, then 1 core is at 4ghz, and the others are at base speed, maybe even sleeping, so if the application just reports the average clockspeed, I can see it arriving at this number.

Can you read out the clock speed for all 12 cores separately, like hwinfo64, but just for linux?

[mikat]

8 minutes ago, Origami Cactus said:

Maybe what you are using doesn't adequately report ryzen clock speeds. When single core load, then 1 core is at 4ghz, and the others are at base speed, maybe even sleeping, so if the application just reports the average clockspeed, I can see it arriving at this number.

Can you read out the clock speed for all 12 cores separately, like hwinfo64, but just for linux?

Oh yeah that's it, using `grep "MHz" /proc/cpuinfo` I can see it is working, thank you

 

Didn't realize linux handled this differently than windows, very used to just using windows task manager.

Every 0,2s: grep "MHz" /proc/cpuinfo

cpu MHz         : 2163.245
cpu MHz         : 2164.101
cpu MHz         : 2119.335
cpu MHz         : 3941.924 <-- my program :)
cpu MHz         : 2083.296
cpu MHz         : 2068.435
cpu MHz         : 2167.127
cpu MHz         : 2150.844
cpu MHz         : 2164.694
cpu MHz         : 2164.620
cpu MHz         : 2173.278
cpu MHz         : 2162.330
cpu MHz         : 2147.448
cpu MHz         : 2469.906
cpu MHz         : 2156.120
cpu MHz         : 3777.464
cpu MHz         : 2074.508
cpu MHz         : 2096.003
cpu MHz         : 2162.750
cpu MHz         : 2151.859
cpu MHz         : 2168.285
cpu MHz         : 2174.605
cpu MHz         : 2167.663
cpu MHz         : 2166.842