Mark, I saw something similar when we first went to SLES-9 (64 bit). We had
MTU sizes being negotiated down to an idiotic packet size of 1492.
Whether or not this has to do with how our OSA is configured I never did learn.
Search for stuff with hipersockets and MTU in the archives for the
particulars.
We reported it to Novell. They eventually managed to test on SLES 9 under
z/Series and eventually issued a patch. They sent us this file:
iputils-ss021109-147.2.PTF.184411.0.s390.rpm
I don't know whether or not this file is GA but it touched MANY IP related
items, indicating that the problem was pervasive. Once we applied it our
MTU negotiation problem went away. It may or may not have bearing on your
situation, but I offer the information to any and all that might find it
relevant.
-J
Mark Wheeler <[EMAIL PROTECTED]>
Sent by: Linux on 390 Port
<[email protected]>
To
[email protected]
cc
12/14/2006 08:33 AM
Subject
Hipersocket Performance Problem on SLES 9
Please respond to
Linux on 390 Port <[email protected]>
Greetings all,
I've been using real hipersockets for a couple years now. Recently a
significant performance problem with SLES 9 and large MTU sizes was brought
to my attention. I've been using MTU=32760. I set up a test to illustrate
the problem. I built a 256 MB file on one zLinux guest (running under z/VM
5.2 on a z9-109), with enough storage defined so the file could be
completely cached. I then FTP'd it to /dev/null on another server over a
hipersocket connection. Here's what I observed:
SLES8-to-SLES8, MTU=8184, ~75 MB/sec
SLES8-to-SLES8, MTU=32760, ~100 MB/sec (as high as 132 MB/sec)
SLES8-to-SLES9, MTU=32760, ~100 MB/sec
z/VM-to-SLES9, MTU=32760, ~100 MB/sec (from file on VDISK to /dev/null)
z/OS-to-SLES9, MTU=32760, ~25 MB/sec (from disk cache on z/OS)
SLES9-to-SLES9, MTU=8184, ~75 MB/sec
SLES9-to-SLES9, MTU=32760, ~400 KB/sec (not MegaBytes, KiloBytes!)
Has anyone else seen this?
I use 32760 on my hipersocket links so as to be consistent with the 32760
MTU size used on CTC links to other processors owned by my z/VM TCPIP
machine, which is used as the gateway between Linux guests on one machine
and z/OS on the other machines.
Best regards,
Mark Wheeler, 3M Company
----------------------------------------------------------------------
For LINUX-390 subscribe / signoff / archive access instructions,
send email to [EMAIL PROTECTED] with the message: INFO LINUX-390 or visit
http://www.marist.edu/htbin/wlvindex?LINUX-390
----------------------------------------------------------------------
For LINUX-390 subscribe / signoff / archive access instructions,
send email to [EMAIL PROTECTED] with the message: INFO LINUX-390 or visit
http://www.marist.edu/htbin/wlvindex?LINUX-390
