We have a not so complex X-WIndows/Motif App on HP-UX 11.11 that has been ported to RHEL. It mostly fetched data from a Database displays it on basic X-Windows widgets - scroling windows, or canvas to display graphics, push biuttons, etc. This APp has been in use for close to a decade on HP-UX 11.11 and has been performing well accross the WAN using various X-CLients such as Kea-X, eXceed, Reflection-X.
On RHEL -- performance of the rebuilt is dismal accross the WAN but fine if it is on the LAN. The old HP-UX 11.11 version which can stil be run to compare performance is pefectly acceptable performance whilst the RHEL build sucks and it is so sluggish.
Granted the HP-UX 11.11 MOtif and X-Windows (X11R6?) libraries may be very old compared to th RHEL bits -- is it possible that later X11R6 and Motif libraries used to build the RHEL version of the app is more complex at sending X11/Motif primitives accross the network -- that the slowdown is more prevalent on the WAN that it is on the LAN?
The network team has performed sniffer traces onthe network but cannot come up with anything conclusive with hints the issue maybe on our Linux Network Configuration. But we have tested this on 2 Linnux environments already - one Virtual and the other Physical and both yielded the same results. We alsoput in suggested tweaks to the TCP Stack to increase the rmem/wmem windows but to no avail. Below is our current TCP stack tunables:
# Oracle SOftware Network Tunables
net.core.rmem_default = 262144
net.core.rmem_max = 4194304
net.core.wmem_default = 262144
net.core.wmem_max = 1048576
net.ipv4.ip_local_port_range = 9000 65000
# increase Linux autotuning TCP buffer limit
net.ipv4.tcp_rmem = 4096 87380 4194304
net.ipv4.tcp_wmem = 4096 65536 1048576
Is there anything more that we can tune? THe Linux servers use Gigabit same as the old HP-UX 11.11 server and are both housed in the same Data Center from which the WAN clients access the app.
Hakuna Matata.
