Freeradius as a loadbalancer - logging dropped accounting requests

AleŇ° Rygl ales at rygl.net
Mon Jun 26 16:23:59 CEST 2017


Hi Alan,

 
>   Then it's a transient load issue.  Either there are peaks higher than the
> system can handle, or something else on the system is stealing CPU time.
> > I was monitoring the number of threads and it is constant
> > all the time and there is really big headroom provide by config.
> 
>   You can configure "max_requests" as high as you want, but if the system is
> starved for CPU, it will still drop packets.

FR is using up to 140% CPU of 48 core system (256GiB RAM, SSD array) I have reniced it and assigned real-time ionice class, the overall CPU of the system is about 20%.
 
>   I've tested FR in simple configs at 20K packets/s on low-end systems.  If
> you're getting less than that (and you likely will), it's because the
> back-end database is slow, or the system is CPU starved, etc.

There is no logging to file, no database in loadbalancer config. It does not even listen for authentication. I can disable all unnecessary modules that could slow it down. There is no attributes rewriting or so. I need just accounting balancing with a really minimalistic config.

>   If you're losing packets at 1000 packets/s, FreeRADIUS is not the cause.

It must be a misunderstanding. The overall drop rate of LB is about 4,6e-05 and drops are finally solved by a retransmission. I was just wonder if there is a way how to detect/log drops or avoid them by config optimisation.

Thanks
Ales



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