Quoting Patrick: | Hi, | | Quick question on iperf and kernel 2.6.22 (official and exp DCCP tree). | I use 2 computers + 1 netembox in between | Here are iperf cmd lines I use : | on dccpServer : # iperf -s -Xdccp -l1424 | on dccpClient : # iperf -c dccpServer -Xdccp -l1424 -t30 This iperf variant only sends at full/maximum speed, i.e. it will try aggressively to stuff your link, until it is forced to slow down by the kernel. This generates a lot of other problems - such as increase in delay, queue overflow etc. I haven't done bandwidth tests during the last days, but if you are doing such tests can you please compare with the constant-bitrate variant of iperf: * use original source http://www.erg.abdn.ac.uk/users/gerrit/dccp/apps/iperf/zip/iperf-2.0.2.tar.gz * only needs patch #1 from http://www.erg.abdn.ac.uk/users/gerrit/dccp/apps/iperf/patches/ * then try iteratively with the -b switch to increase the bandwidth, i.e. iperf -c dccpServer -l1424 -d -b1m # 1Mbps CBR DCCP iperf -c dccpServer -l1424 -d -b5m # 5Mbps iperf -c dccpServer -l1424 -d -b10m # 10Mbps Do you get a higher speed this way? If yes, then the low speeds are likely due to queue overflow, otherwise there is another reason. There have been a lot of changes in the netdev kernel, the test tree has not been changed. | | On 2.6.22 kernel: | Without netem rate control, iperf result is about 95.0 Mbits/sec | With netem rate control at 1024Kbits/sec, iperf result could be | 10Kbits/sec or 30Kbits/sec... | | On 2.6.20 with Ian's patches: | Without netem rate control, iperf result is about 95.0 Mbits/sec | With netem rate control at 1024Kbits/sec, iperf result is about 950Kbits/sec. | | netem cmd lines: (I also tried with delay and loss turned on) | tc qdisc add dev eth0 root handle 1:0 tbf rate 1024kbit buffer 10000 limit 30000 | tc qdisc add dev eth1 root handle 1:0 tbf rate 1024kbit buffer 10000 limit 30000 | | Is anyone has a such low rate on 2.6.22 kernel? do you know why? | | regards, | Patrick. | | | On 17/07/07, Ian McDonald <ian.mcdonald@xxxxxxxxxxx> wrote: | > On 7/18/07, ツ Leandro Sales <leandroal@xxxxxxxxx> wrote: | > > Hi, | > > | > > I'm using iperf to make some DCCP tests and I'd like to know if it | > > is possible to make iperf client (with -c option) transmit packets | > > during certain duration and measure the throughput each x seconds. | > > I've used -t 3 (for instance) option, but iperf just connect, send | > > packets, show the results and finish its job. I'd like to continuous | > > take instant throughput for each x seconds, how to do this? | > > | > > []s | > > Leandro. | > | > From iperf --help | > -i, --interval # seconds between periodic bandwidth reports | > | > I use this quite a bit and works perfectly. I've also modified iperf | > to run continuously if you need that capability - available from my | > web page. | > | > Ian | > -- | > Web: http://wand.net.nz/~iam4/ | > Blog: http://iansblog.jandi.co.nz | > WAND Network Research Group | > - | > To unsubscribe from this list: send the line "unsubscribe dccp" in | > the body of a message to majordomo@xxxxxxxxxxxxxxx | > More majordomo info at http://vger.kernel.org/majordomo-info.html | > | - | To unsubscribe from this list: send the line "unsubscribe dccp" in | the body of a message to majordomo@xxxxxxxxxxxxxxx | More majordomo info at http://vger.kernel.org/majordomo-info.html | | - To unsubscribe from this list: send the line "unsubscribe dccp" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
