[CentOS] 1 Gbit/s Ethernet NIC under CentOS

Ross Walker rswwalker at gmail.com
Sat Dec 4 01:55:51 UTC 2010


On Dec 3, 2010, at 7:48 PM, Gordon Messmer <yinyang at 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




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