Re: Tuning GigE network for cluster computing?

On Sat, Jun 03, 2006 at 09:28:42AM -0700, Danial Thom wrote:

<sgk@xxxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote:

First, I'm running FreeBSD 6.1-stable on a
small cluster
with 6 nodes that contain Tyan motheriboards.
These broads
have Broadcom GigE NICs that use the bge
device.

The cluster will be using MPI to possibly shove
large data
sets through a GigE switch, so I'm trying to
determine how
best to optimize the transfer.

Would DEVICE_POLLING and/or jumbo frames likely
methods for
enhanced speeds?


Firstly we've been discussing how bad and
inefficient the broadcom controllers are. If you
have a tyan MB with onboard controllers they are
incredibly slow (ie inefficient), as well as
being quirky. If you have a PCI-X slot put in an
intel card. They have built-in interrupt
moderation so you don't have dick around with
polling. A 133Mhz intel controller (make sure
they have the GB chips on them and not the EB)
will use half the cpu of the on-board broadcoms.
If you don't believe try it with one box and
measure the cpu usage before and after. Its worth
the $50. investment in the card, believe me.

I'll look into the Intel cards, but unfortunately
I'm probably stuck with the onboard broadcom devices
for the immediate future. There is one expansion
slot (whether its PCI-X, I don't know). I was
actually planning to use the slot for infiniband,
myrinet, or the 10 GiGE cards that Drew Gallatin
has mentioned.

While polling may marginally decrease the cpu
load (depending on how bad FreeBSD 6.1 is on
interrupt overhead), its also going to add
latency to the processing of packets, which is
the opposite of what you want to do.

This is the conclusion that I reached in reading
i386/conf/NOTES. Thanks for confirming my suspicions.

--
Steve
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