Re: After upgrading from Debian 11 to Debian 12, the latency became worse

On 22.06.26 12:42, mars_liu wrote:
> 
> 
> Hi xenomai,
> 
> We have a new machine. When we installed Debian 11 (kernel version 5.10.199, Xenomai version 3.2.4), the latency test results were quite good — the maximum latency didn't exceed 40 µs. However, after upgrading to Debian 12 (kernel version 6.1.121-cip34, Xenomai version 3.2.6), the latency got worse, with the maximum exceeding 100 µs.  What caused this change? The new kernel was built using the old kernel configuration. Is it possible to optimize the latency in Debian 12 by tweaking the new kernel configuration?
> 
> New machine: Giga Computing MW53-HPU0；CPU：Intel Xeno w3-2425
> 
> Thanks for any suggestions. I've attached my configuration.
> 

Can you try to systematically eliminate variables that may contribute to
the increase? E.g., use the old kernel with its original configuration
on the new installation or go back to the original Xenomai version.

If the kernel is the cause, checking once more if the effective config
of 6.1 is not missing or adding suspicious things compared to the
effective 5.10 kernel config.

An alternative is obviously turning on tracing and record one of those
events that are longer than expected. At least basic event traces
(cobalt events) should not increase latencies on their own a lot while
giving a general overview what happens.

Jan

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