ideal RAM memory allocation ?

I'll give you the benefit of the doubt and assume that you didn't really read my last post instead of replying with a snarky comment about how you are not a power user of either platform.

Try running Visual Studio 2005 and Office 2007 with just 512 mb of RAM and get back to me on how well that works out for you. Never mind trying to develop against Office SharePoint Server 07 which needs at least 1 GB of RAM. *sigh*

As you've said, the less RAM you allocate to the guest the better, but sometimes the guest needs a bit more. It would be nice if I could change the guest memory allocation on the fly. This is a feature offered by competitors and it would be great to have in Parallels as well.

 

It would be nice if I could change the guest memory allocation on the fly.

I second this (if parallels is listening). I infrequently use the three applications I run that suffer from my modest allocation to the guest. Shutting down really defeats much of what I find appealing about virtualization.

 

I'd like some input from the memory experts ;-)

I attached a screenshot of Vista Ultimate, configured with 512 MB RAM. I am not sure how to read all the stats, but I feel that the vm is running a bit sluggish and there seems to be a lot of disk swapping going on. I also changed the caching policy from vm to host OS, in order to (hopefully) improve performance of OS X.

According to this screenshot, should I increase the RAM for the vm? I have 2 Gig total RAM in my MBP.

Thanks,

D

 

You really need to get some applications going and get that CPU out of the cellar to know for sure if you have enough RAM. If you do not then there will be a lot of swapping. What you have looks pretty normal to me.

 

Not sure what you mean by cpu out of the cellar?

and I did forget that the screenshot was with MS Outlook 2007 running, but no other programs.

D

 

Vista handles memory management differently than it's predecessors. It considers unused memory "wasted" so it spends time filling it up with things it thinks you might need. It should dump the 'precached' memory quickly if you do something that is unexpected, but the net is that high memory usage on Vista doesn't indicate a problem. I'd do the standard stuff first, like defragment your guest OS, try and defragment the swap file (pagedefrag from www.sysinternals.com) and then see how performance goes.

 

thanks,

boy I can tell you that the vm is dragging butt since I changed the caching policy from vm to OS X....what an impact. I even upped the allocated RAM to 640 Mb but it's still dragging. Next I'll change the caching policy back and see what happens.

D

 

At 5% cpu usage that system isn't doing anything - certainly not exercising memory management. Start up some applications that do work so you can get a real profile of the VM's performance. Even silly things like Pinball and Solitaire in demo mode help along with a powerpoint presentation, etc.

 

For us non-experts, could you please explain what you mean by changing the caching policy?

Thank you,

David

 

There is a hard-disk caching policy option under the virtual machine settings. I changed it from vm to OS X, and while OS X became more responsive, the vm was just bad. I just now changed it back to vm, and Vista seems a lot more responsive and quicker to respond. Now I haveto deal with a less responsive OS X though

Seems like a trade-off either way. Not sure what the best solution is for this setting....


D

 

In the VM realm everything is a compromise. I think things will get better when Parallels offers support for two or more CPU's. I can't help but think there's a lot of context switching going on in the one-and-one CPU mode currently used.

 

Actually devoting 1 CPU to VM and 1 to OSX results in much less context swapping. Devoting 2 CPU cores to the VM will result in OSX running even slower.

darreln - what applications are you running in you Vista VM? And simultaneously what applications are your running in OSX? Are you running in coherence mode? Do you have USB and sound enabled? Within Vista itself, what UI effects do you have enabled?? Have you tried disabling some of those effects? Within Vista do you have any antivirus or other background processes enabled?

 

VTMac, I run primarily Outlook and MS OFFice apps in the vm. I dissabled all fancy stuff except the Vista theme. USB support is disabled, sound is on and not running coherence. I do run more apps in OS X all across the board.

As I said, with the HDD caching turned back to the vm, things are now a lot more speedy again. I thinkn that this is going to be the best performance I can expect "right now". as was noted, development continues, and we can all hope that performance will become must quicker down the road!

D

 

How does that play out in a heavily threaded world? Windows has pre-emptive threads where for example, Solaris does not. If memory serves. BTW, this has not been my experience with Fusion and the non-scientific tests I've run. I'd have thought the Parallels model would act like processor bound applications. Come to think of it I don't recall what the thread model is in OS X.

 

Virtualizing both processors will only help if the VM is CPU bound. In most office type application sets, CPU is not the limiting factor. It is much more like to be something I/O related like Disk or Network or Memory. Virtualizing 2 CPUs for the VM, means that a poorly written application (or guest OS) can "impose it's will" on OSX by not playing nice with both processor cores. Also, the VM hypervisor will have to deal with concurrency issues (and the associated context swaps that concurrency introduces) that it presently doesn't have to address with only a single core. Virtualizing both cores for guest VMs will very likely make the guest VMs more responsive, but it will do some at some cost. As with all else in the VM world, nothing is free.

 

darreln - Well, I'm sorry to say I'm fresh out of ideas to help you. I would suggest that if you have XP, you setup an XP VM just to see for yourself the performance difference. In my experience it is significant. If you don't have a specfic requirement for Vista, I'd recommend XP. Especially since it sounds like you've disabled a lot so the vista eye candy.

Alternately, you could disable the Vista theme temporarily to see it's impact.

 

Ok -- this is consistant with what I expected. The choices for optimization are to bring up a VM with the least impact to the host, bring up a VM and to hell with the host, the VM is there to do all the work, and bring up a VM and balance all elements so that the host and guest are getting maximum work done. I'm in the latter camp with Parallels, and the second case for most other platforms. My view is the host is there to make and manage VM's, and the VM's are there to make money. That's kind of a datacenter view of it. My workstation I want to get the most out of both sides. I need to build applications and test builds in Solaris and Linux, and I need to get my book keeping, mail, and daily grind stuff done in OS X.

All my other servers that run VM's do so with all processorss shared though in Solaris I can specify how much each will get from the CPU's. I'm kind of spoiled on that kind of management capability. Parallels and Fusion are end-user products so I have to keep my expectations somewhat shy of what I'd prefer.

 

oh, no problem. You guys have been a lot of help. I am more happy with the caching policy back in place. Things are running good. I think, with time, Vista will be further optimized both by MS and also by Parallels...

D

 

Where can I find the criteria for determining whether one is a "true macintosh power user"?

 

The fact that you have to ask this question, only furthers the point that you are not a "true macintosh power user"! If you were you would have received the secret decoder wheel, password, and handshake long ago.