Poor TCP loopback throughput on Windows

Posted by Yodan Tauber on Server Fault See other posts from Server Fault or by Yodan Tauber
Published on 2010-11-28T09:05:19Z Indexed on 2011/03/17 8:11 UTC
Read the original article Hit count: 166

Filed under:

Windows

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networking

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Performance

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tcp

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sockets

I measured the throughput of a locally bound TCP socket connection on my computer (Intel Q9550, 64 GB RAM, Windows XP 64 bit) using iperf. I got dissatisfying results (around 1.6 Gbit/s) each time, no matter how I tweaked the TCP settings (buffer length, window size, max segment size, no delay). I got similar results when I tried netperf.

Now, I understand (from sources like these) that the average throughput of a loopback connection should be around 5 Gbit/s. What could be the reasons for such poor performance?

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