On Dec 3, 2010, at 7:48 PM, Gordon Messmer yinyang@eburg.com wrote:
On 12/03/2010 03:48 PM, Ross Walker wrote:
If the protocol is latency sensitive then jumbo frames are BAD as it adds more latency because frames take longer to fill, longer to transmit and thus other conversations have to wait longer (poor pipelining/interlacing).
CIFS/NFS aren't really latency sensitive protocols though. If a protocol has a big TCP window then it will not tend to be latency sensitive.
I measure better throughput on NFS with jumbo frames than without. Measurement trumps assertions. :)
All I was trying to get across is that jumbo frames aren't to be used in latency sensitive applications as it adds latency.
As your findings show NFS is not a latency sensitive application and thus why you see better throughput with jumbo frames. That is also why NFS/CIFS can be used over a WAN while a latency sensitive protocol such as iSCSI is almost useless over the WAN.
-Ross