[dpdk-dev] "No probed ethernet devices" caused by inaccurate msec_delay()

Thomas Monjalon thomas.monjalon at 6wind.com
Mon Jan 27 10:19:00 CET 2014


27/01/2014 03:56, Sangjin Han:
> Cause: No probed ethernet devices - check that
> that CONFIG_RTE_LIBRTE_IXGBE_PMD=y in your configuration file
> I googled for possible causes and came across a similar case:
> http://openetworking.blogspot.com/2014/01/debugging-no-probed-ethernet-devi
> ces.html
>         msec_delay(4);
> I think /proc/cpuinfo is not a reliable way to get
> eal_tsc_resolution_hz, since it varies based on the current CPU clock
> frequency. Enforcing applications to run at the max frequency can be
> too restrictive.

Indeed, as described in the quick start page, the highest frequency must be 
set: http://dpdk.org/doc/quick-start

> It would be nice if I can bypass set_tsc_freq_from_cpuinfo() in
> set_tsc_freq().

I think it would not solve the problem because your clock is varying and the 
TSC calibration must be updated accordingly with different values by core.

Feel free to submit a patch if you find a smart solution.

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