Demystifying Vista memory usage

People are still afraid of Vista memory usage, even after reports of successful installation on some pretty old hardware.

It's true: Vista needs more memory than XP, but not as much memory as people may think. I believe the problem arises because of a Vista memory management policy: Vista tends to use memory unused memory! This is policy Unix users are used to, but not to Windows users.

Let me give you an example: on a recent machine Vista tends to use about 650MB PF usage on a clean install. This scares too much users, who think they won't ever be able to install it on a 512MB machine, or even use it on a 1GB one. On a previous post, I reported a successful installation on a 512 MB Celeron, reporting half the memory usage (ok, no Aero here).

But yesterday I had the most interest hint of PF usage somehow misleading information: on my Vista installation, when booting the first OS, VMWare player freezes the OS for 30 seconds or so. I decided to investigate, and the results were:

• Vista was reporting about 900MB of PF usage (I had outlook, IE7, an RSS reader and some utilities running)
  
• I booted VMPlayer VM
• PF usage rose to 2GB, leaving Vista stalled for about 30 seconds
• PF usage dropped to 372MB!
• PF usage slowly increased to 450MB, as VMPlayer claimed more memory

Uau! What's the meaning of this? A simple explanation could be: Vista is claiming way more memory than XP, but can live without it. Using this "unused" memory, Vista can boost a lot of operations, and above all, leave the disks idle. When that memory is needed for applications, Vista will free it.

If this is true, Vista is probably not being particularly assertive. The first problem with this is that Vista is misleading the memory management information - shouldn't it be marked as cache? The second problem with this approach is that it scares users away.

If this is true, people will probably write utilities that will claim and release memory just to keep users happy, loosing some of Vista's memory management capabilities.

Can anyone please confirm or deny this behavior?

PS: I'm telling you Vista does may need less memory than it tells you, I'm not advising you not to upgrade your memory with Vista. Let me be clear about it: if you can afford to spend 40 bucks, do yourself a favor and get more 512MB of memory.