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I am currently testing openstack for windows guests (XP and 7). I have deployed openstack "all in one" on system with following specs

Processor corei5. (4 physical cores and 8 Threads with HT Technology)

RAM 8 GB.

HD 500 GB.

I have created 4 windows xp guests with 512MB RAM and 1VCPU.

On each windows guest i have installed visual studio 2008 only.

In nova.conf CPU Over-Commit ratio is 2 for better performance (as mentioned in openstack operation guide).

Using KVM as hyerpvisor.

I have observed poor performance when simultaneously using visual studio in four windows instances. How i can improve performance ? Should i use KVM or Hyper-V ? or any other suggestion ?

user198851
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  • I'd suggest testing both platforms and seeing what works well for you as there's no single magic answer. I would however suggest that your biggest performance issues are probably down to using a 12 year old operating system with a totally inadequate amount of RAM on each guest to run a platform that's well known for being resource-hungry, far more than your choice of hypervisor. – Rob Moir Nov 10 '13 at 09:10
  • After executing visual studio 2008 it occupy only 350mb of RAM on windows xp instance. On comparing with bare metal system with same specs and environment its performance is excellent. – user198851 Nov 10 '13 at 10:07
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    Ah, no. You udont use visual studio, right? "Occupy only 350Mb" is "without doing anything". That is sort of totally counter-productive. I manage to get Visual Studio up to nearly 3gb when I do profiling for a complex application - a lot more if the application uses data caching extensively. Granted, not that outdated version of Visual Studio (which has a lot less powerfull debuiggger), but even that I managed to get close to 1.5gb with Resharper in a larger project. – TomTom Nov 10 '13 at 13:00
  • Not to mention, is Visual Studio really the workload you intend to run?! That's better run on a local workstation. – Michael Hampton Nov 10 '13 at 17:10
  • Well i think my question is not off-topic. it is related to openstack cloud configuration for better performance of windows instances. Can u please elaborate how my question is off topic – user198851 Nov 11 '13 at 06:59

1 Answers1

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Hyper-V - no question here.

Not becasue of performance but because all viretualization is fully integrated and maintained as part of windows updates. No need to install anything unless you run outdated windows versions.

That said:

HD 500 GB

Welcome to the reality of virtualization. It does not makgically make crappy hardware faster. A 500gb HD is not good to run visual studio - unless if is a Velociraptor - because it will be slow. Running multiple computers on one such hard disc is like saying "hey, my Fiat Panda is too slow when i load up 2 tons of stuff into the trunk". HD overload is a likely cullprit. Possibly also the crappy RAM:

RAM 8 GB

Yes. That is crappy. Really. See:

I have observed poor performance when simultaneously using visual studio in four windows instances

Let me be clear - 4gb PER VM is too low to run Visual Studio properly (with debugging etc.). Cramming 4 such instances into what is less than 2gb physical memory per Computer (as a VM is a computer) is asking for trouble.

That is totally not related to the virtualization technology. You simply need to put (a) an SSD into the thing (or an array of faster discs) and (b) put enough RAM into the server to run the workloads you want to run.

It gets worse when you see:

I have created 4 windows xp guests with 512MB RAM and 1VCPU

What about you run VIsual Studio on a physical computer with 512mb RAM. HINT - IT WONT WORK FAST. 1VCpu - bad, too low (I dont allocate less than 2 virtual CPU's these days) and seriously, 512Mb RAM for something as ressource hungry as Visual Studio. WHOOOOOA. WAAY too low.

Try 4gb per VM. And a fast disc subsystem.

TomTom
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  • Well i have physical computer with same specs 512mb RAM and 3.0 GHZ single core processor. It works perfectly for intial level visual studio applications.. But on cloud i have observed poor performance even with cpu-overcommit ration of 1 means 1VCPU = 1 Physical core... The problem seems to be with processing speed not with RAM or hard disk – user198851 Nov 10 '13 at 15:40
  • If you're going to keep on arguing when two people independently tell you the same thing, why bother asking? In any case, Visual Studio will continue to be resource intensive and to not care whether you think so or not. – Rob Moir Nov 10 '13 at 16:00
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    1VCPU is anything but a 1 core commitment. You lack a basic understanding how virtualization works on PC's - the last time saw that as a rule was on mainframes. – TomTom Nov 10 '13 at 16:20
  • @RobM IM just asking for learning purpose. Arguing is not bad thing. I have tested both environments how can i just say " Yeah you are right" to anyone even to Bill Gates – user198851 Nov 10 '13 at 17:36
  • if cpu-allocation ratio is 20 then 20 VCPU will use 1 core.[The default CPU allocation ratio of 16 means that the scheduler allocates up to 16 virtual cores on a node per physical cores](http://docs.openstack.org/folsom/openstack-ops/content/compute_nodes.html) – user198851 Nov 10 '13 at 17:52
  • Overcommit is irrelevant untless the cpu is utilized. Seriously. I have some not so small Hyper-V servers - we talk of 64gb memory here - and most are idloe most of the time in the CPU. It really depends what you do. On others, you can not overcommit - 1vcpu is 1physical core or your performance suffers, as the CPU is basically hot 24/7. Common sense is not something to ignore when planning - and virtualization needs quite some of it. No standard rule will ever work. – TomTom Nov 10 '13 at 21:44