Re: Network packet loss possible inside the linux kernel?

Daniel Kay <daniel-kay2@xxxxxxxx> wrote:
Hello folks!

I am currently planning to implement an easy way to communicate
between multiple processes on the local machine. Every process may
sends events (in form of a null terminated string) as multicast UDP
messages. The other processes react on these events if required.

How likely is it, that packet loss may occur? My hope is, that
because these messages are processed without a physical network,
that I can ignore the packet loss issue.

It can happen and you should assume it will. Here is just a plain
unidirectional test showing a few losses:

hpcpc105:~/netperf2_trunk# src/netperf -t UDP_STREAM
UDP UNIDIRECTIONAL SEND TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to localhost (127.0.0.1) port 0 AF_INET
Socket Message Elapsed Messages
Size Size Time Okay Errors Throughput
bytes bytes secs # # 10^6bits/sec

124928 65507 10.01 205949 0 10784.03
124928 10.01 205946 10783.87

hpcpc105:~/netperf2_trunk# uname -a
Linux hpcpc105 2.6.23-rc3-minrtoms #1 SMP Tue Aug 21 15:21:54 PDT 2007 ia64 GNU/Linux

And it does not require sending anything particularly large:

hpcpc105:~/netperf2_trunk# src/netperf -t UDP_STREAM -- -m 1460
UDP UNIDIRECTIONAL SEND TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to localhost (127.0.0.1) port 0 AF_INET
Socket Message Elapsed Messages
Size Size Time Okay Errors Throughput
bytes bytes secs # # 10^6bits/sec

124928 1460 10.01 1792715 0 2092.08
124928 10.01 1790784 2089.83

rick jones
--
denial, anger, bargaining, depression, acceptance, rebirth...
where do you want to be today?
these opinions are mine, all mine; HP might not want them anyway... :)
feel free to post, OR email to rick.jones2 in hp.com but NOT BOTH...
.