I've tried it on variety of different servers/hardware using both my server+apachebench and netperf as benchmarking tools.
* On EC2 I've tried the c1.xlarge and the giant cc1.4xlarge. With cc1.4xlarge, I saw maybe a ~10% increase accept() rate.
* Two separate, virtualized servers at the office.
* A private, virtualized server on Rackspace was briefly tested as well.
I doubt it'll reveal anything super useful, but running your tests on a single-tenant EC2 instance could add an extra datapoint. I suspect it'll only reveal that the problem _isn't_ due to EC2/Xen swapping your virtualized machine out. (assuming you haven't tried it already...)
* On EC2 I've tried the c1.xlarge and the giant cc1.4xlarge. With cc1.4xlarge, I saw maybe a ~10% increase accept() rate. * Two separate, virtualized servers at the office. * A private, virtualized server on Rackspace was briefly tested as well.
A compilation of netperf results are available at https://gist.github.com/985475