OT: PC Gigabit Throughput Question

Mark Komarinski mkomarinski at wayga.org
Fri Jun 15 11:22:57 EDT 2007


On 06/14/2007 08:30 PM, Ric Werme wrote:
> A 1500 byte Ethernet message is 12,000 bits, and hence only 12 usec of
> wire time.  If you need full performance and can use "Jumbo Frames"
> of 9,000 bytes (72 usec) so much the better.
>   
The other advantage of jumbo frames is that there's less packet overhead
so more data/time, and far less overhead for the CPU to assemble the
frame, calculate checksums, etc.  The speed in my testing wasn't
necessarily faster, but you did save 10-20% CPU load when running at
high data rates.  Devices that have a lot of large-IO blocks (file
servers) would have a boost in improvement when switching to jumbo
frames.  We'd be using it on our cluster, but some of the older nodes we
have don't support jumbo frames on the Ethernet chipset.  Once those get
retired, we'll probably move to jumbo frames.

-Mark


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