Lousy Network Performance

[Kurt Wall]

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
-- 
Anthony's Law of Force:
	Don't force it; get a larger hammer.