We now feel that Dummynet on FreeBSD-3.3 is reliable enough to
use for the bake-off tests. Thus, we propose to change to make this
change to 3.3 (instead of 3.1) in order to keep the packet loss
and delays in the bake-off workload.
The dummynet parameters that we will use are:
Polygraph Servers: 55 msec delay, 0.05% loss
Polygraph Clients: 75 msec delay, 0.1% loss
We've found that dummynet works best when you have one "pipe" for
incoming packets, and another for outgoing packets. It can be
configured using these commands:
ipfw -f flush
ipfw pipe 1 config delay 75ms plr 0.001
ipfw pipe 2 config delay 75ms plr 0.001
ipfw add pipe 1 ip from any to 10.8.0.0/16 in
ipfw add pipe 2 ip from 10.8.0.0/16 to any out
(you will need to change "10.8.0.0" to match your own configuration).
Since we add the low-level packet delays, we propose to decrease
the Polygraph server-side "think-time." Currently it is norm(3sec,1.5sec).
We'd like to use norm(2.5sec,1.0sec) instead.
For your convenience, we have set up a FreeBSD-3.3 kernel source
tree that has all of the changes needed for the bake-off environment.
This tree is available via rsync. You can get it with this
# rsync -a -v ftp.ircache.net::freebsd33-bakeoff-sys /usr/src/sys
Our source tree includes the following changes:
* TCP MSL lowered to 3 seconds
* Raised system-wide MAXFILES to 32K
* Added "atomic = 1" patch so that writes slightly
larger than one mbuf are not delayed.
* Alex's "addr_hash" patch that implements interface address
lookups with a hash table instead of a linked list.
This archive was generated by hypermail 2b29 : Tue Jul 10 2001 - 12:00:10 MDT