On Wed, 05 Sep 2007, Jesper Dangaard Brouer wrote: > On Tue, 2007-09-04 at 13:40 -0400, Bill Fink wrote: > > On Tue, 04 Sep 2007, Patrick McHardy wrote: > > > > > Bill Fink wrote: > > > > On Sat, 1 Sep 2007, Jesper Dangaard Brouer wrote: > > > > > > > Yes, you need to specify the MTU on the command line for > > > jumbo frames. > > > > Thanks! Works much better now, although it does slightly exceed > > the specified rate. > > Thats what happens, with the current rate table system, as we use the > lower boundry (when doing the packet to time lookups). Especially with a > high MTU, as the "resolution" of the rate table diminish (mpu=9000 gives > cell_log=6, 2^6=64 bytes "resolution" buckets). > > > [EMAIL PROTECTED] ~]# tc qdisc add dev eth2 root tbf rate 2gbit buffer > > 5000000 limit 18000 mtu 9000 > > > > [EMAIL PROTECTED] ~]# ./nuttcp-5.5.5 -w10m 192.168.88.14 > > 2465.6729 MB / 10.08 sec = 2051.8241 Mbps 19 %TX 13 %RX
That doesn't seem to account for the magnitude of the rate exceeding. In the worst case (rough calculation): (1+64/9000)*2000 = 2014.2222 Mbps Now if that were 256 rather than 64: (1+256/9000)*2000 = 2056.8888 Mbps Or maybe the packet overhead is calculated wrong for the 9000 MTU case (just wild speculation on my part). -Bill - 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