Re: KVM performance Java server/MySQL...

[Gleb Natapov <gleb@redhat.com>]

On Thu, Feb 07, 2013 at 04:41:31PM +0100, Erik Brakkee wrote:
> Hi,
> 
> 
> We have been benchmarking a java server application (java 6 update 29)
> that requires a mysql database. The scenario is quite simple. We open a
> web page which displays a lot of search results. To get the content of the
> page one big query is done with many smaller queries to retrieve the data.
> The test from the java side is single threaded.
> 
> We have used the following deployment scenarios:
> 1. JBoss in VM, MySql in separate VM
> 2. JBoss in VM, MySQL native
> 3. JBoss native, MySQL in vm.
> 4. JBoss native and MySQL native on the same physical machine
> 5. JBoss and MySQL virtualized on the same VM.
> 
> What we see is that the performance (time to execute) is practically the
> same for all scenarios (approx. 30 seconds), except for scenario 4 that
> takes approx. 21 seconds. This difference is quite large and contrasts
> many other test on the internet and other benchmarks we did previously.
> 
> We have tried pinning the VMs, turning hyperthreading off, varying the CPU
> model (including host-passthrough), but this did not have any significant
> impact.
> 
> The hardware on which we are running is a dual socket E5-2650 machine with
> 64 GB memory. The server is a Dell poweredge R720 server with SAS disks,
> RAID controller with battery backup (writeback cache). Transparent huge
> pages is turned on.
> 
> We are at a loss to explain the differences in the test. In particular, we
> would have expected the least performance when both were running
> virtualized and we would have expected a better performance when JBoss and
> MySQL were running virtualized in the same VM as compared to JBoss and
> MySQL both running in different virtual machines. It looks like we are
> dealing with multiple issues here and not just one.
> 
> Right now we have a 30% penalty for running virtualized which is too much
> for us; 10% would be allright. What would you suggest to do to
> troubleshoot this further?
>

What is you kernel/qemu versions and command line you are using to start
a VM?
 
--
			Gleb.