Thanks for the reply! I'll check the receiving side. Could you please point me to an article/discussion describing the blocking- and non-blocking NIC drivers? I didn't find it from iperf-users mailing list..
regards, Martin On 8/21/14, Metod Kozelj <metod.koz...@lugos.si> wrote: > Hi, > > > Martin T je dne 21/08/14 15:53 napisal-a: >> if I executed "iperf -c 10.10.10.1 -fm -t 600 -i 60 -u -b 500m" in a >> virtual-machine with GigE vNIC, then Iperf client(version 2.0.5) under >> Debian sent traffic at 120Mbps during all the intervals. If I replaced >> the OS in virtual-server with CentOS, the same Iperf release with the >> same command was able to send traffic at 500Mbps. > > There used to be a discussion on this mailing list a few weeks ago ... some > > linux kernel drivers (together with IP stack drivers) work in blocking mode, > > and some in non-blocking mode. The difference, visible for application, is > that in blocking mode application will not be able to TX more data until > driver buffer gets flushed (enough) while in non-blocking mode kernel driver > > will discard data when buffers are full. > > What you should tell us is the following: what kind of performance do you > see > on the receiving side? Is it the same as on sending side (in both OS cases) > or > is it much different for either of OS choices? I would guess that the real > GigE vNIC is around 120Mbps and Debian exposes that to iperf while CentOS > drops data and thus hiding real performance from iperf. > -- > > Peace! > Mkx > > -- perl -e 'print > $i=pack(c5,(41*2),sqrt(7056),(unpack(c,H)-2),oct(115),10);' > -- echo 16i[q]sa[ln0=aln100%Pln100/snlbx]sbA0D4D465452snlb xq | dc > > ------------------------------------------------------------------------------ > > BOFH excuse #178: > > short leg on process table > > ------------------------------------------------------------------------------ Slashdot TV. Video for Nerds. Stuff that matters. http://tv.slashdot.org/ _______________________________________________ Iperf-users mailing list Iperf-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/iperf-users
