On Wed, 1 Feb 2006 19:02:02 +0100 Andi Kleen <[EMAIL PROTECTED]> wrote:
> On Wednesday 01 February 2006 17:52, Ben Greear wrote: > > > I haven't been able to get a TCP connection to saturate a 1Gbps link > > in both directions simultaneously. I *have* been able to fully saturate > > 2 pro/1000 NICs on the same machine using pktgen, so the NIC/driver can > > support it if only TCP can run fast enough... > > I remember someone complaining that this (back to back gigabit TCP > saturation) > worked with 2.4 and stopped with 2.6. My guess back then was NAPI, but even > disabling that didn't fully solve it. > > If you can reproduce that (it working with 2.4) then it might be useful if you > could: > - Try to figure if there are any interesting difference between the two > runs in netstat -s > - And perhaps do some packet capture of the 2.4 and 2.6 runs and run them > through tcptrace (http://jarok.cs.ohiou.edu/software/tcptrace/) and do a diff > between the two. > Also, you have to increase TCP max window size to saturate a 1Gbps link. You need to increase tcp_rmem[2] on receiver and tcp_wmem[2] on sender. This is easily done with sysctl. And of course you have to have enough memory that TCP isn't deciding to throttle you for chewing too much memory in the system (see tcp_mem) -- Stephen Hemminger <[EMAIL PROTECTED]> OSDL http://developer.osdl.org/~shemminger - To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
