John, On Tuesday 31 August 2004 21:23, John Andersen wrote:
On Tuesday 31 August 2004 07:08 am, Randall R Schulz wrote:
I have to concur with this. The overhead for the virtual machine is not negligible and the fact that two competing OS vye for resources in a way they were never designed to do (i.e., cooperatively) mean neither OS will perform as well as you're accustomed to.
Say what?
The one OS is running under the other OS. They don't compete any more than any other software competes for cycles.
Neither Linux or Windows is written with a VM environment in mind. They both assume they have complete control of the machine. Neither end up operating as responsively in a VMware configuration on any given physical hardware setup as they would without VMware and the other OS present. The VM context switching cost alone constitutes an irreducible overhead that comes out of total available cycle count. Since each OS at a minimum takes clock interrupts, this overhead never goes away, even if all the useful work is happening on one side of the host / guest divide.
Vmware is nothing but a process under Linux, (or vise versa if Vmware is running on a windows host). They get along just fine. Performance is good on adequate hardware. (For some values of Adequate, given some values of good).
I didn't say they don't "get along," just that both OSes plus VMware itself all consume cycles and none of them can get 100% of the machine as an OS normally does when running on physical hardware.
Vmware is great for emulating the entire machine, we use it for software development all the time. Yes it is a bit of a dog but anything over a P4 1.6ghz with over half a gig of ram works very snappy. We uses it for windows software development with several VMware machines running at the same time (talking to each other over tcpip. You just can't do this type of testing under wine or Coo.
VMware is great, no doubt about it. Naturally WINE (and CrossOver Office) do not compare, nor do they really aim to. However, my experience using VMware on a 2.4 GHz Pentium 4 with 1 Gb of RAM was not necessarily what I'd call "snappy." Then again, on that system it had some problems that VMware's tech support never managed to solve (my needs changed and I gave up trying to get the problem resolved). So perhaps I never experienced its full potential on that system. Before that the last time I used it was back in the late 90s on systems with Pentium II and III processors running in the few to mid hundred MHz clock speed range. Randall Schulz