Re: channel bonding for myrinet

On Tue, 2003-01-07 at 20:58, [email protected] wrote:
> hello,
> 
> In www.myri.com/scs/faq/faq-gm.html#gmq13,the main interest of channel
> bonding for myrinet is in high availability,as the performance of two IP
> over Myrinet devices aggregated will be less than one device.But why?while
> in general ethernet bonging can increase the bandwidth.

Not all of the time. Channel bounding makes TCP packets arriving out of
order. As the host processing is already the bottleneck for IP over GM 
with one NIC, increasing the host overhead by doing more re-assembly
won't improve the performance. When the link is the real bottleneck like
with Fast Ethernet, channel bounding for performance makes sense. With
Gigabit Ethernet, it's questionable.

> In addition,channel bonding is only support by IP over myrinet.If I want to
> implement bonding on GM over myrinet to achive 300MB bandwidth,how do I do
> it? Can I imitate bonding for IP over myrinet?

If you have 2 NICs in one machine and enough PCI bandwidth, you can open
2 GM ports in your application and either send half of your messages on
each port or part of each message on each port. If you have more skills,
you can implement it at the firmware level (with GM firmware. it's not
trivial).

The easiest way is actually to wait for the Lanai 2XP, with 2 links on
the faceplate.

Patrick
-- 

Patrick Geoffray, Phd
Myricom, Inc.
http://www.myri.com