732056 - test INIT_CWND=10 kernel on stage zeus

Status: RESOLVED FIXED

(Cloud Services :: Operations: Miscellaneous, task)

Description

[:Atoll]

While investigating INIT_CWND 10 this morning, ckolos discovered that the very latest RHEL 6 kernel has the new default, which may improve our response times to clients.

09:14 <@ckolos> looks like all we'll have to do is yum upgrade kenrel
09:15 <@ckolos> for 6.1 that pulls the 220.4.2.el6 kernel

So, we should come up with some sort of A/B test and run it.

Comment 1

[Jeff Vier [:jvier]]

on this topic:
http://www.reddit.com/tb/ldjwf
http://samsaffron.com/archive/2012/03/01/why-upgrading-your-linux-kernel-will-make-your-customers-much-happier

Comment 2

[:Atoll]

quoting ldjwf above:

On receiver side (requires kernel version 2.6.33 or newer (and a fairly new iproute package. iproute2-ss100519 works). Use your default route instead of "x.x.x.x"):
ip route change default via x.x.x.x initrwnd 20
On sender side:
ip route change default via x.x.x.x initcwnd 20
To tweak both send and receive:
ip route change default via x.x.x.x initcwnd 20 initrwnd 20

or we can take the samsaffron route and upgrade to RHEL's latest kernel

Comment 3

[:Atoll]

the kernel rewrites the provided initcwnd to a maximum of 4 without http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff;h=442b9635c569fef038d5367a7acd906db4677ae1

Comment 4

[:Atoll]

Okay, let's try out the new kernel you suggested along with the latest Zeus kernel module from http://community.riverbed.com/t5/Extensions/Zeus-Kernel-Modules-for-Linux/td-p/16620

For each server in zlb.scl2.stage.svc, zlb.pub.scl2.stage.svc:

# chkconfig --del zeus
# service zeus stop
# yum blah kernel blah
# shutdown -r now
# wget http://community.riverbed.com/rvrb/attachments/rvrb/Extensions/9/1/zeus_modules_installer-2.4.tgz
# tar -xzvf zeus_modules_installer-2.4.tgz
# cd zeus_modules_installer-2.4
# ./install_modules.pl
# service zeus start
# chkconfig --add zeus

And once all servers are upgraded, a load test will be required.

Comment 5

[:Atoll]

:petef linked http://code.google.com/speed/articles/tcp_initcwnd_paper.pdf

Comment 6

[Chris Kolosiwsky [:ckolos] (ckolos has left the building)]

requires the following additional packages to be installed

kernel-devel
kernel-headers

and for this particular action, gcc required an upgrade as well

Comment 7

[James Bonacci [:jbonacci]]

For Loadtesting, best choice will be BID.
We are having some troubles running Sync load and AITC/TS load right now...