Interrupt mitigation / coalescing question

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Interrupt mitigation / coalescing question

Mihai Tanasescu-2

I don't know if this is the right list to ask so if I've posted to the
wrong one please correct me.

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
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 ?

2. Will the mp kernel perform better or worse ? (I saw some benchmarks
which showed it could perform worse).