Network Performace

[Karl Pielorz]

--On 23 June 2003 18:12 -0700 Shawn Ramsey <shawn at cpl.net> wrote:

> I am having some issues with network performance and am wondering if
> anyone has any suggestions... the box in question has 2 100BT interfaces,
> and an Intel (em driver) fiber Gigabit. The Gigabit connects to a switch,
> and the two fast-e are WAN connections to our ISP(s). This box seems to
> be using an awful lot of CPU cycles relative to the traffic it is
> pushing, which is around 65-70Mb inbound, and 20-30 Mb/outbound(on
> average), which seems to be about its limit. This is an Athlon XP 1500
> box, 256MB RAM, top shows 90+% interrupt usage, CPU usually has about
> 5-10% idle. Gigabit is on a 32-bit bus, and Gigabit is on an IRQ shared
> with unused USB and onboard NIC which is also not used. Should I be able
> to push more than 100Mb sec with such a system? It is not doing anything
> else, no NAT, one IPFW rule. OS is FreeBSD 4.7-RELEASE.

All depends how big the packets are etc. - 90% interrupt time is fairly 
typical of x86/PC kit shoveling lots of small packets.

Try looking into FreeBSD's "polling" mode - i.e. interrupt free Network 
cards. If your shifting a lot of small packets (such as online gaming stuff 
etc.) - you may find your milage pretty limited using standard PC kit - as 
the x86 architecture wasn't really designed for shifting lots of small 
packets around [as I've seen many a time in the past :(]

-Kp