netisr process eats 100% cpu

[Dmitry Sivachenko]

> On 10 сент. 2015 г., at 19:45, Dmitry Sivachenko <trtrmitya at gmail.com> wrote:
> 
> Hello!
> 
> I am using fresh FreeBSD-10/stable.
> 
> I have a program which establish a TCP connection to server and sends a lot of small requests over it.
> I put haproxy load balancer working in TCP mode in the middle, which listens some port on localhost.
> 
> Under the relatively low network load (20MB/sec, ~100 kpps), netisr process starts to consume close to 100% CPU, and does not allow to utilize more network bandwidth:
> 
>   11 root         -72    -     0K   944K CPU27  27   0:34  98.06% intr{swi1: netisr 0}
> 
> If I do not pass traffic through haproxy but connect directly to remote server, netisr process consumes 0% CPU and everything works well.
> 
> Is it rather expected or this can be fixed?
> 
> Thanks in advance.


Also I want to add that netisr process consume CPU only when TCP client and haproxy are running on the same host.  If I move haproxy to a separate machine, netisr process does show in top(1) output at all.

So this looks weird at least.