[Click] Userlevel performance issues

[Beyers Cronje]

Hi Robert,


> *       We first found that when UserLevel Click started pulling from a
> PCAP file, the performance of the ToDevice() appeared to drop sharply.
> What I mean by this is that the ToDevice() pull handler reported values
> in the range of 200 packets/second once the PCAP file started reading.
> This resulted in the outbound queue just prior to the ToDevice() filling
> up and eventually overflowing because the packet rate in the PCAP file
> is far more than 200 packets/second.


You dont have to use a queue between FromDump and ToDevice as FromDump is an
agnostic element. In other words you can connect Todevice directly to
FromDump which should ensure that at least no packets are dropped and you
should see best ToDevice performance.

Also there are a few tuning parameters. Try tuning your NIC TX Ring size. On
the e1000 driver the default TX ring size is 256, experiment with different
value to see if it makes a difference.ToDevice uses a packet socket from
transmit, so it might be worth experimenting with
/proc/sys/net/core/wmem_default
/proc/sys/net/core/wmem_max

Beyers