Since they're running on one physical machine, and since there is no flow control with UDP, unlike TCP, your transmitter is probably overrunning your receiver resulting in dropped packets. On 2010-03-06, at 3:02 PM, mpsingh wrote: > Hi all, > > I am experimenting with virtual machines existing in the same physical > machine. > > My configuration is:- Native: opensuse,/xen and tool used is "iperf" > > I am getting TCP throughput of around 8Gbps between two VM. but the UDP > throughput is around 1.53 Gbps at data rate of 3000Mbps. but with this the > data loss is around 20-30% > > I tinkered with linux kernel settings to tune the TCP sockets > r|w _mem = 4096 12288 262144 > r|w _ default = 12288 > r\w_max = 2262144 > RTT = 0.096 ms > txqueuelen = 10000 > backlog queue= 2000 > > the above setting are done in both VMs and in the Dom0. > > Earlier I got UDP performance of 1.8 Gbps with negligible data loss. I dont > know those settings in the kernel. > I am not getting the optimum settings to get around this problem. > > Thanking you in anticipation > -- > M P Singh > Carleton University, Ottawa > +1 613 422 8074 > _______________________________________________ > Linux mailing list > Linux [ at ] lists [ dot ] oclug [ dot ] on [ dot ] ca > http://oclug.on.ca/mailman/listinfo/linux