Lousy Network Performance

[James McDonald]

On Wed, Jun 29, 2005 at 12:03:57AM -0400, Kurt Wall wrote:
> On Tue, Jun 28, 2005 at 02:29:43PM +1000, James McDonald took 0 lines to write:
> > On Mon, Jun 27, 2005 at 10:56:34PM -0400, Kurt Wall wrote:
> > > Hi, list,
> > > 
> > > How do I go about solving a significant latency problem on my
> > > internal network. I have two computers connected via a crossover
> > > cable, eth1 on the "server" (luther) to eth0 on the "desktop"
> > > (easter). Both cards are 10/100. Ping time is atrocious:
> > > 
> > > I can't see any reason why the latency should be so extreme.
> > 
> > If you are using a crossover cable check your duplex settings. I have found performance gains by either enabling/disabling duplex.
> > 
> > Use a tool like ttcp to push raw packets back and forwards... You should be getting around 100Mbps. 
> 
> Using ttcp, I didn't even get 10Mbit/sec:
> On the sending machine, I ran
> # ./ttcp -t -s -f m easter
> ttcp-t: buflen=8192, nbuf=2048, align=16384/0, port=5001  tcp  -> easter
> ttcp-t: socket
> ttcp-t: connect
> ttcp-t: 16777216 bytes in 18.00 real seconds = 7.11 Mbit/sec +++
> ttcp-t: 2048 I/O calls, msec/call = 9.00, calls/sec = 113.78
> ttcp-t: 0.0user 0.0sys 0:18real 0%
> 
> On the receiving machine, similarly:
> # ./ttcp -r -s -f m
> ttcp-r: buflen=8192, nbuf=2048, align=16384/0, port=5001  tcp
> ttcp-r: socket
> ttcp-r: accept from 192.168.0.1
> ttcp-r: 16777216 bytes in 18.00 real seconds = 7.11 Mbit/sec +++
> ttcp-r: 2921 I/O calls, msec/call = 6.31, calls/sec = 162.28
> ttcp-r: 0.0user 0.0sys 0:18real 0%
> 
> Kurt
Try setting the duplex to half using the miitool or ethtool or whatever and then rerun your tests. Unfortunately I have found that some of the linux drivers perform nowhere near the same as their Windows counterparts. However the 'hi end' cards. 3Com, Intel, IBM etc or anything they put in a Server system provided by the factory with Linux on it will probably work really well.

Often times these failures aren't noticed because the box is used to browse the internet it's only when you try to back up your box on your homem lan and discover it's as slow as a dead dingos donger that you realise you have a problem... 


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