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From "Steve G.B." <stefano.guidoba...@yahoo.it>
Subject RE: Installing Multiple Instances on Windows Server 2003
Date Tue, 02 Sep 2008 12:37:59 GMT

It's a Quad Core Intel Xeon with 4GB of RAM and ESX running on it.

I've created a VM with 4 VCores, and all of the cores are allocated to the
VM.

I'm using Sun JVM 1.6, and stressing the Guest with Loadrunner on another
machine (if you ask: this machine with loadrunner isn't the bottleneck)

No Databases, no I/O requests, no Network saturation.

that's why I think it's the JVM.
For my tests I used the standard demo webapp in Loarunner (Mercury Tours),
and a couple of stupid jsp pages. So Apache and Tomcat both. 

Fun thing is that when using Tomcat and Apache combined, I can get an 80-85%
CPU Utilization. Problem is that for my tests I need something more simple
and the same server.

So today I've installed the second Tomcat running calling the same jsp page
of the other.

No think time set.

How do you saturate an 8-core host?

Please help me :)

Stefano


Peter Crowther wrote:
> 
>> From: Steve G.B. [mailto:stefano.guidobaldi@yahoo.it]
>> I'm trying to overload the Virtual Machine on which I've
>> installed the two Tomcats.
> 
> To check: this is a virtual computer (on a physical host computer) running
> a virtual operating system on which you are running two copies of Tomcat
> in two separate Java virtual machines?
> 
>> But I can't exceed a 50% of CPU Utilization.
> 
> How many virtual cores have you set up?  How many physical cores on the
> host computer do you have?  How many of those are allocated to the virtual
> computer?
> 
>> I believe it's a JVM limitation.
> 
> What JVM are you using?  If it's a Sun one, I don't believe you ;-).  I've
> saturated 8-core processors on 1.4 and 1.5 with no issues; I can't see
> that having regressed in 1.6, although I don't have personal experience.
> 
>> Is there a way to change jvm configurations
>> in order, for example, to create even more threads?
> 
> Depends on your JVM.  But I'm willing to bet that the bottleneck is in one
> or more of:
> - Your test harness;
> - Your web app (do all the threads access a common object?);
> - A library you're using that single-threads;
> - Your back-end systems, such as your database server.
> 
>                 - Peter
> 
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> 

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