Just to bring everyone up to speed (it's been a while): I've done more testing and so far have seen this only between two SLES9 systems. Things run fine up to MTU=32084; at MTU=32085 and above throughput drops to ~400KB/sec. Problem has been reported to SuSE but haven't heard back from them.
What do others use for hipersocket MTU size? Mark > > 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 > ---------------------------------------------------------------------- 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
