Re: Network performance - iperf
From: Rick Jones
Date: Mon Mar 29 2010 - 12:47:40 EST
I don't know how to set fixed socket buffer sizes in iperf, if you were running
netperf though I would suggest fixing the socket buffer sizes with the
test-specific -s (affects local) and -S (affects remote) options:
netperf -t TCP_STREAM -H <remote> -l 30 -- -s 32K -S 32K -m 32K
to test the hypothesis that the autotuning of the socket buffers/window size is
allowing the windows to grow in the larger memory cases beyond what the TLB in
your processor is comfortable with.
Particularly if you didn't see much degredation as RAM is increased on something
like:
netperf -t TCP_RR -H <remote> -l 30 -- -r 1
which is a simple request/response test that will never try to have more than
one packet in flight at a time, regardless of how large the window gets.
happy benchmarking,
rick jones
http://www.netperf.org/
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