Slow LOCALHOST iperf on Windows (on esxi)

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andy

Member
Oct 10, 2016
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Canada
I'm running about 6/7 versions of windows (desktop/server) on esxi and iperf/network performance are pretty bad.

I'm using R610's R620/R720's and I have 2 tests I try.

The first is iperf with localhost and the server and client. I'll get ~2Gbps on the 610's and ~1.5gbps on the newer servers. The second test is a ram disk over a 10G fiber network, which results in about the same speeds. (But for the external tests I do use jumbo packets and RSS)


I don't think it's network related since some tests don't even use a nic, and with the same basic OS install on a dell 790 i5 I'm getting almost 8Gbps REAL throughput to an identical machine over 10G fiber.

Also all VM's have tried with 4/16 vcpu's.

Any suggestions? All power management is turned off on all esxi hosts.
 
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manfri

Member
Nov 19, 2015
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I'm nott an esxi expert but i think that even localhost connectivity is not completery software based but can (and must) use the hardware resource of nic to reach speed beyiond the one you see.
in an hyperv i will check the nic for vmq capabilities, i do not know if esxi use vmq at all...
 
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coolrunnings82

Active Member
Mar 26, 2012
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I just spent a good part of my afternoon troubleshooting very similar performance to this on my R720. Interestingly enough, OmniOS, virtualized on my Supermicro system gives nearly 40Gbps when running iperf against localhost.
 
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