Per-Olov Sjvholm wrote:
I have read that people have tested with *very* high load with success...
I am not the best expert....but you don't say anything about the OpenBSD
config. At high load you probably have to change net.inet.ip.ifq.maxlen,
kern.maxclusters, net.inet.tcp.recvspace, net.inet.tcp.sendspace,
net.inet.tcp.rfc1323, kern.somaxconn among some other things... If you for
example run out of "maxclusters" the server will freeze (as you mentioned)...
Try OpenBSD FAQ ;-)
Again, net.inet.tcp.recvspace, net.inet.tcp.sendspace, rfc1323 sliding
window support and kern.somaxconn has nothing to the with routing
performance.
kern.maxclusters specifies the maximum number of mbuf clusters and I've
never seen a system freezing because of exhausted mbuf clusters. Recent
kernels are intelligent enough to tell they're out of mbuf clusters via
kernel messages. It can be easily traced from /var/log/messages.
BTW, FAQ's section 6.6 has no recommendations about tuning routing
performance.
After 3.8, major performance gains regarding cpu/interrupt load has been done
in the em driver among many other fixes in the driver. Can't see you even
mention the OpenBSD version you use....
And another thing... SMP kernel wont help if (but you don't) you run PF as it
can't make use of SMP. Maybe it could be worse... But I don't know for sure.
MP makes possible to use I/O APICs so offloads the interrupt load from
CPU. It can be big plus.
When it comes to the NIC;s, many on the list will probably tell you the marvel
chip is a good one. But you probably know that if you read the list. But it
will probably wont help you if you don't tune the server right anyway...
There doesn't exist many user configurable knobs to achieve high
forwarding and packet handling performance if you don't come up with
ultra secret kernel patches.
