Excerpts from Usman S. Ansari's message of Sun Nov 28 12:36:44 -0600 2010: > > Appreciate if someone can shed light on this. > > I am running iperf on two systems connected via 10 GB cards. I am seeing lot > of > difference between through put reported by server and client. > > Iperf threads Through put report Gb/s > (by server) / (by client) > 3 8.68 / 8.68 <=== same === > 4 8.61 / 9.47 <=== different === > > In past I have seen differences in through put reported by server and client, > but not by this much. > > Can someone tell why this is so and which number to trust ?
When asking for help like this, please be sure to include the versions of Iperf used during a test as well as brief summary of the OS and hardware that is used on each host. The actual Iperf output is usually helpful as well. Is this a TCP or a UDP test? For a TCP test I'd expect them to be pretty close. If those numbers are from a TCP test I'd like to hear more about your setup. Sometimes they are off a little bit due to the fact that the interval of time used to calculate the throughput might vary a bit on client and server. Sometimes the UDP numbers vary a bit because with UDP it's just blasting packets out without any flow control. In this case the server number is the accurate number since it will be what it was able to receive. That will at least be a lower bound. It turns out that UDP reception can be difficult even for fairly beefy hosts so sometimes the packets are lost a receive time. Jon -- Jon M. Dugan <[email protected]> ESnet Network Engineering Group Lawrence Berkeley National Laboratory ------------------------------------------------------------------------------ Increase Visibility of Your 3D Game App & Earn a Chance To Win $500! Tap into the largest installed PC base & get more eyes on your game by optimizing for Intel(R) Graphics Technology. Get started today with the Intel(R) Software Partner Program. Five $500 cash prizes are up for grabs. http://p.sf.net/sfu/intelisp-dev2dev _______________________________________________ Iperf-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/iperf-users
