CPU affinity, P-Cores slower than E-Cores?

[Trust9]

Hey guys,
I have a strange problem.
My test system has an Intel 14900k installed.
I wanted to use the E-Cores for unimportant VMs and the P-Cores for intensive VMs.

I have assigned the P-Cores to the same VM once and the E-Cores once. I tested both with:

sysbench cpu --cpu-max-prime=20000 --threads=$(nproc) run

Here is the result of the P-Cores:

CPU speed:
    events per second: 16078.27

General statistics:
    total time:                          10.0009s
    total number of events:              160809

Latency (ms):
         min:                                    0.52
         avg:                                    0.99
         max:                                    8.79
         95th percentile:                        1.01
         sum:                               159980.70

Threads fairness:
    events (avg/stddev):           10050.5625/41.13
    execution time (avg/stddev):   9.9988/0.00

and the result of the e-cores

CPU speed:
    events per second: 27244.27

General statistics:
    total time:                          10.0006s
    total number of events:              272482

Latency (ms):
         min:                                    0.58
         avg:                                    0.59
         max:                                    3.77
         95th percentile:                        0.59
         sum:                               159962.42

Threads fairness:
    events (avg/stddev):           17030.1250/56.85
    execution time (avg/stddev):   9.9977/0.00

How can this be? Only this one test VM is running on the host.
I repeated the tests several times

Thanks

 

[Neobin]

You are comparing 8 cores / 16 threads (8 threads being from HT) from the P-cores against 16 cores from the E-cores.
Iirc, at least in the past, one HT-thread gives/gave as most around 30% performance of one core.
So, a better comparison, in this case, would imho be 8 P-cores vs. 8 E-cores.

I do not say, that your results are expected, because I simply have no, respectively did not look for any other, comparison; but you might want to search the web for similar comparisons of P-cores vs. E-cores on a 14900K, to see if your results indeed are to be expected or not.

Just a hypothesis of mine...

 

[kevinshane]

I have the same exact result of a 13900hx (8x2p, 16e) with 250tdp unlocked

# p core
CPU speed:
events per second: 13647.55
General statistics:
total time:                          10.0012s
total number of events:              136503
Latency (ms):
min:                                    0.60
avg:                                    1.17
max:                                    2.73
95th percentile:                        1.34
sum:                               159988.55
Threads fairness:
events (avg/stddev):           8531.4375/751.39
execution time (avg/stddev):   9.9993/0.00

# e core
CPU speed:
events per second: 23957.45
General statistics:
total time:                          10.0007s
total number of events:              239614
Latency (ms):
min:                                    0.66
avg:                                    0.67
max:                                    5.16
95th percentile:                        0.68
sum:                               159971.16
Threads fairness:
events (avg/stddev):           14975.8750/10.94
execution time (avg/stddev):   9.9982/0.00