[Dnsmasq-discuss] dnsmasq using 100% cpu on router

[Rick Jones]

>
> The first thing is to try and decide which of two possible scenarios ar
> happening. The first is that you've triggered a bug in the code and
> dnsmasq is looping somewhere without ever getting back to the select()
> loop and doing actual work. The second is that it's getting so much work
> that it's running out of CPU to do it.
>
> In the first case, dnsmasq will stop working entirely. Is that
> consistent with  "problems resolving addresses" or does it still
> partially work? Turning off logging is probably counter-productive here,
> the logs may have valuable clues.

And if indeed the dnsmasq process is simply being inundated then 
presumably its socket(s) will start overflowing which should trigger a 
netstat somewhere.  For the DNS portion that would be something in 
netstat -s I would think, the UDP section.

Knowing how much of this 100% CPU time is user space versus 
system/kernel would be goodness, as might a system call trace (eg strace)

happy benchmarking,

rick jones