Optiplex 755

zz912
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03 Mar 2023 23:30 #265811 by zz912

Optiplex 755 was created by zz912

Hello,

I have interesting problem. I have old computer. Everything is OK. Latency test is around 50 000. This is nice. But sometimes I get message about bad latency. So I made tests in MesaCT configurator:

The test went wrong. I do not want increase Servo Thread Period.

Is my computer weak for Mesa? Can something be done about it? Or should I just order a more powerful PC.

I tried using only the basic configuration from PNCconf and using LCNC 2.8.0. The values improved, but only slightly.

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PCW
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04 Mar 2023 01:05 #265813 by PCW

Replied by PCW on topic Optiplex 755

Did you disable AMT in the BIOS?
Disable IRQ coalescing?

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zz912
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07 Mar 2023 15:52 - 07 Mar 2023 16:11 #266029 by zz912

Replied by zz912 on topic Optiplex 755

I think, coalescing is off:

[code]jarda@CNC1:~$ sudo ethtool -c enp0s25
Coalesce parameters for enp0s25:
Adaptive RX: off  TX: off
stats-block-usecs: 0
sample-interval: 0
pkt-rate-low: 0
pkt-rate-high: 0

rx-usecs: 0
rx-frames: 0
rx-usecs-irq: 0
rx-frames-irq: 0

tx-usecs: 0
tx-frames: 0
tx-usecs-irq: 0
tx-frames-irq: 0

rx-usecs-low: 0
rx-frame-low: 0
tx-usecs-low: 0
tx-frame-low: 0

rx-usecs-high: 0
rx-frame-high: 0
tx-usecs-high: 0
tx-frame-high: 0

jarda@CNC1:~$

[/code]

Bios has not got anything like AMT.

Last edit: 07 Mar 2023 16:11 by zz912.

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PCW
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07 Mar 2023 16:23 #266036 by PCW

Replied by PCW on topic Optiplex 755

Its in ME setup (needs a password) I think AMT is enabled by default on the 755

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zz912
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07 Mar 2023 16:42 - 07 Mar 2023 17:01 #266040 by zz912

Replied by zz912 on topic Optiplex 755

Is ME setup in BIOS?

Edit: ME is MEBx

Last edit: 07 Mar 2023 17:01 by zz912.

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PCW
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07 Mar 2023 17:04 #266042 by PCW

Replied by PCW on topic Optiplex 755

Yes, you probably have to enable the MEBx message to access is through the BIOS setup
(and hope that the BIOS gives you access to AMT setup)

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zz912
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07 Mar 2023 17:36 #266047 by zz912

Replied by zz912 on topic Optiplex 755

I disabled it, but it did not help.

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PCW
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07 Mar 2023 18:03 #266049 by PCW

Replied by PCW on topic Optiplex 755

Well its necessary but maybe not all that's needed

What kernel are you using?
(its known the the default Debian RT kernels are not very good)

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zz912
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07 Mar 2023 18:30 #266052 by zz912

Replied by zz912 on topic Optiplex 755

Hello,

1) Kernel is in Pictures

2) I have new knowledge. We can rule out a Mesa card error. A latency-test is enough to simulate the problem. Look at the following picture:

As soon as I start the latency test, the message immediately starts:

Unexpected realtime delay on task 0 with period 25000
This Message will only display once per session.
Run the Latency Test and resolve before continuing.

In this image, I managed to simulate that the error message only appeared after a while. Nevertheless, the latency-test showed satisfactory values. Why?

3) I tested branche 2.8.0 and 2.9. Both is same.

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07 Mar 2023 18:56 #266053 by PCW

Replied by PCW on topic Optiplex 755

A latency error may be expected with a 40 KHz
base thread but Its not too meaningful though because:

1. A base thread is not needed with Mesa hardware
2. The important thing is Ethernet latency which the latency test doesn't measure

You can get an idea of Ethernet latency with:

sudo chrt 99 ping -i .001 -q 10.10.10.10

(let run for a few minutes and then control-C)

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Optiplex 755

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