Re: Linux Firewall: Hardware questions: interrupts and network cards
On Wed 23 Nov 2005, Theodore Knab wrote:
>
> I have Xeon 700MHz Netfinity running as campus firewall managing
> about 10K - 300K sessions on a T3. It runs the 2.6.8 kernel and
> IPtables in bridge mode.
>
> When I use 2 cpu's the systems seems to get interrupt collisions. Are
> interrupt collisions common with dual CPU systems on Linux firewalls ?
Why do you say "seems to get interrupt collisions", what are the
symptoms? Here we don't have any such problems (firewall that handles
200Mbit/s routinely, all sorts of traffic, although a large chunk is
web).
> Also, are there any good network cards that have 2 - 3 ethernet ports on them and
> only require 1 IRQ ? I think multiple port PCI cards would offer greater preformance
> than 2 or 3 separate PCI cards. Correct me if I am wrong.
You're wrong :) A multiple port PCI card is typically built using a PCI
bridge on the card, hence creating a new PCI bus. This extra level of
indirections won't help. Each interface will still be separate. Having
all share the same interrupt is typically not that useful.
Paul Slootman
Reply to: