Poor application performance in VM

Six6siX

Six6siX

Six6siX

Soldato
Joined
25 Nov 2004
Posts
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Location
Hertfordshire
Hi,

Not sure if this is the right place for this question...

I have a LISP based simulator application that runs without issues on the hardware natively but as soon as it is put in a VM, performance becomes quite flakey.

The application is quite sensitive to timings so CPU (and to some extent network performance) are important. I have tried HyperV and VMWare based setups but results are generally the same.

I appreciate this is quite a vague question but is there anything to look into that would improve stability when running in a VM? I've experimented with number of cores and priority/affinity both within the VM and resource priority on the hypervisor, fixed disks, memory etc.

Is there anything else?

Cheers.
 
Off the top of my head!!!

Check that the VM isn't paging memory to disk, if so increase memory?

Adding cores may not help if the application is predominantly single threaded and could decrease performance. If the application is CPU cache intense sharing CPU with other VMs could cause lots of cache flushes and reloads slowing down the application. In this case try reserving/fixing CPU resources for this VM.

If the application is one of many VMs on this host try reserving/fixing physical memory. You could also try switching HT off, some applications, especially older ones don't work well with HT enabled.

If the host has multiple physical CPUs ensure NUMA support is enabled in the bios.
 
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