lkml.org 
[lkml]   [2007]   [Nov]   [6]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: bizarre network timing problem
Felix von Leitner wrote:
> Thus spake Rick Jones (rick.jones2@hp.com):
>
>>Past performance is no guarantee of current correctness :) And over an
>>Ethernet, there will be a very different set of both timings and TCP
>>segment sizes compared to loopback.
>
>>My guess is that you will find setting the lo mtu to 1500 a very
>>interesting experiment.
>
> Setting the MTU on lo to 1500 eliminates the problem and gives me double
> digit MB/sec throughput.

I'm not in a position at the moment to test it as my IPoIB systems are offline,
and not sure you are either, but I will note that with IPoIB bits circa OFED1.2
the default MTU for IPoIB goes up to 65520 bytes. If indeed the problem you
were seeing was related to sub-mss sends and window probing and such, it might
appear on IPoIB in addition to loopback.

rick jones
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2007-11-06 22:15    [W:0.030 / U:0.132 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site