Re: [Xen-users] Bad TCP accept performance

[Pasi Kärkkäinen <pasik@xxxxxx>]

On Wed, May 25, 2011 at 10:04:18AM -0400, Russ Purinton wrote:
>    Correct, using 127.0.0.1 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.
> 

Using localhost (127.0.0.1) goes thru loopback device only, ie. interface 'lo',
so it does NOT go through NIC card or xen/PV drivers..

> 
> 
>    How well 127.0.0.1 performs however is kind of a moot point however as no
>    real application would make use of this. 
>

That's true.


-- Pasi


> 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 (127.0.0.1) 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
> 
>    [1]http://cgbystrom.com
> 
> References
> 
>    Visible links
>    1. http://cgbystrom.com/





_______________________________________________
Xen-users mailing list
Xen-users@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-users