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RE: [Xen-users] Bad TCP accept performance

To: Carl Byström <cgbystrom@xxxxxxxxx>, Pasi Kärkkäinen <pasik@xxxxxx>
Subject: RE: [Xen-users] Bad TCP accept performance
From: "Russ Purinton" <rpurinton@xxxxxxxxxxxxxxxxxxxxxxx>
Date: Wed, 25 May 2011 10:04:18 -0400
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Thread-topic: [Xen-users] Bad TCP accept performance

Correct, using should allow the VM to make a ridiculous amount of TCP connections to itself (max ~65000 concurrent) in a very short amount of time, however the loop back address is still ‘in’ the NIC card so those tests do not really stay self contained in the VM, it does need to go thru the PV drivers to the virtual network layers and back, however what it does accomplish is that you can rule out pretty much anything external to the physical host as a test.  I’m not sure if you mentioned using PV drivers or not but that’s definitely a good idea.


How well performs however is kind of a moot point however as no real application would make use of this.  The real test is how many you can spin up from a physical host outside of the virtualization platform.   There’s also value in knowing how many you can make from VM to VM.


Here is a test I have running across the open internet…  (See attachment)


This breaks down the server response time by how long it took for DNS to resolve, how long it took to create the TCP connection, how long it took after the connection established to start feeding data, and how long it took to feed all the data.   Also through graphing network responsiveness it shows how much of the result is due to network response vs server response.  Running a test like this while you flood the server might also help to gauge the weakest point and how much load you can actually handle (which is ultimately the final question).


The server in the report above is behind a 10Mbit Fiber link, but this product is capable of testing up to 2Gbit/sec in a virtual environment.  Feel free to contact me FMI



From: xen-users-bounces@xxxxxxxxxxxxxxxxxxx [mailto:xen-users-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of Carl Byström
Sent: Tuesday, May 24, 2011 5:46 PM
To: Pasi Kärkkäinen
Cc: xen-users@xxxxxxxxxxxxxxxxxxx
Subject: Re: [Xen-users] Bad TCP accept performance



Russ, I tried this using only local loopback ( to minimize any external factors. Does that make a difference to what you were suggesting?


Appreciate any help I can get on this.



Carl Byström

Attachment: AppViewWebReport_20110525095123.pdf
Description: AppViewWebReport_20110525095123.pdf

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