Gus Wirth wrote: > James G. Sack (jim) wrote: >> Gus Wirth wrote: >>> Andrew Lentvorski wrote: >>>> Gus Wirth wrote: >>>>> If I do an NFS mount and copy a large file from the server to >>>>> /dev/null on the client or if I scp a file between the server and >>>>> client I get pretty much the same results, about 11MB (that's bytes) >>>>> per second. This is only about 10% better than 100baseT ethernet. I >>>>> know from previous experiments that my hard drives and general system >>>>> throughput can handle about 25MB/sec. >>>> If you are seeing 10 MibiBytes per second on a 100baseT, you >>>> effectively have no network traffic on it. Must be nice. That's one >>>> reason why you are seeing practically no increase. >>> This is my home network, with currently only two machines running. But I >>> would have expected to about double my transfer speed based on my >>> current system capabilities. >>> >>>> Second, I think you need to bump the default TCP packet size. On a >>>> network that small, the TCP window is probably filling and throttling >>>> the transfer rate. >>>> >>>> Make sure your systems are sending 9000+ byte packets rather than just >>>> 1500+ byte packets. >>> OK, off to the man pages to figure out how to do that. >> >> maybe: >> ifconfig eth0 mtu 9000 > > That's it. Unfortunately, it breaks networking. Or more specifically, it > breaks when network packets exceed 1500 bytes. Setting the MTU of either > machine causes something to choke and the connection dies. > > For example, I set MTU=9000 on both machines. I monitor the connection > on the server with Ethereal. I start a scp operation from the server to > the client. The initial exchange and negotiation of the ssh keys goes > fine. However, as soon as a data packet gets transmitted that's bigger > than 1500 bytes, the transmit queue starts to back up and I stop getting > any replies from the client. It's really weird and I'm not sure what I > should be looking at. I'm thinking I should get a gigabit crossover > cable (is there such a thing?) and try without the switch to eliminate > that as a potential problem. > > On the other hand, I now know about the ip command, sysctl, ethtool, and > a bunch of stuff in /proc/sys/net, none of which fixes my problem. >
It was my understanding that GigE automatically adjusted itself so that crossover cables have no impact, and are never needed. ..jim -- [email protected] http://www.kernel-panic.org/cgi-bin/mailman/listinfo/kplug-list
