We run latency tests against "ProLiant DL110 Gen10 Plus" servers with "iLO Firmware Version2.72 Sep 04 2022" in our pipelines. We have a biosettings that give Max 14us with 4.10.45 build.

hwlatdetect:  test duration 21600 seconds
   detector: tracer
   parameters:
        CPU list:          None
        Latency threshold: 8us
        Sample window:      10000000us
        Sample width:      950000us
     Non-sampling period:  9050000us
        Output File:       NoneStarting test
test finished
Max Latency: 14us
Samples recorded: 78
Samples exceeding threshold: 78
ts: 1690494043.493348711, inner:14, outer:14
ts: 1690494094.693333933, inner:14, outer:14
ts: 1690494483.813099568, inner:14, outer:14
ts: 1690494575.973091893, inner:0, outer:14

with the same physical server, we run the same test against 4.12.25 builds but  observed high number between 27 ~ 44us.

Thanks Brent R helped take a look.

When he disabled the console driver, we observed inline results:

hwlatdetect:  test duration 43200 seconds
   detector: tracer
   parameters:
        CPU list:          None
        Latency threshold: 8us
        Sample window:      10000000us
        Sample width:      950000us
     Non-sampling period:  9050000us
        Output File:       NoneStarting test
test finished
Max Latency: 12us
Samples recorded: 9
Samples exceeding threshold: 9
ts: 1692019543.521718115, inner:2, outer:9
ts: 1692022728.161717439, inner:9, outer:0
ts: 1692024397.281718973, inner:2, outer:10
ts: 1692033500.640716557, inner:2, outer:12

However, after reboot the server and run again, the lat number will be bigger than 20us.
 
F0815 17:43:06.244852       1 main.go:53] failed to run hwlatdetect command; out: hwlatdetect:  test duration 1800 seconds
   detector: tracer
   parameters:
        Latency threshold: 20us
        Sample window:     10000000us
        Sample width:      950000us
     Non-sampling period:  9050000us
        Output File:       None

Starting test
test finished
Max Latency: 27us
Samples recorded: 1
Samples exceeding threshold: 1
ts: 1692120526.644392602, inner:27, outer:17

Create this ticket to tracking this. 

Load recent 4.12 builds on ProLiant DL110 Gen10 Plus server. run hwlatdetect test.

1. disable the console driver, run the test
2. reboot the server (console driver is running), run the test
3.

with driver running, the lat number > 20us

with driver running, the lat number < 20us

HPE "ProLiant DL110 Gen10 Plus" servers with "iLO Firmware Version2.72 Sep 04 2022"