I have pasted my dmesg output at: http://pastebin.com/450862
I'm quite amazed that I have 50% of the processor busy with interrupts
with only 40.000 pkt/sec traffic between the fxp and em cards.
Should I expect the same result with the sk cards ?
Stuart Henderson wrote:
--On 06 December 2005 12:25 +0200, Mihai Tanasescu wrote:
I don't know if this is the right list to ask so if I've posted to
the wrong one please correct me.
misc@ is better.
I need your opinion on which cards to use to best support interrupt
mitigation / coalescing on an intel xeon 3 Ghz box.
I now have 2 fxp cards on that box and 2 em cards.
I will be expecting a maximum of 120.000-140.000 pkt/sec routing
through it.
Now with only 20-40.000 pkt/sec by using top I see the processor is
50% busy handling interrupts.
I'm getting 10k interrupts on em1 and 10k on fxp1 (I'm using just two
netcards for testing).
I have read the following manpages: fxp, em, sk.
For fxp I saw interrupt coalescing is supported but it requires intel
firmware.
The firmware is redistributable, you should find it in base38.tgz
(/etc/firmware/fxp-d10xxx).
For em I haven't found anything related to interrupt coalescing.
For sk I found ( The XMAC provides the Gigabit MAC and PHY support
while the GEnesis provides an interface to the PCI bus, DMA support,
packet buffering and arbitration) which might suggest support for IRQ
mitigation.
I now have the following questions:
1. What netcards should I use to achieve best results for routing and
less cpu overhead ?
sk.
2. Will the mp kernel perform better or worse ? (I saw some
benchmarks which showed it could perform worse).
Best to try for yourself, I think this depends on your motherboard.
Are you sharing irqs between a nic and other devices? (if you'd
included complete dmesg output, we would already have been able to
see). If you are, you might want to try rearranging things to avoid
that (play with bios settings, disable unnecessary devices using an
irq, maybe change pci slot for the nics).
