【Vista之家译】Vista占用大量内存的真正元凶竟是？

【Vista之家译】谁令vista占用如此大的内存？

　　Windows Vista开机之後会慢慢慢慢慢慢慢慢占更多内存。。。。。最终发现竟然是一个vista的新功能：Superfetch!!

　　Superfetch其实系windows xp里面prefetch的改良版，能力着实强了很多。Vista之家新秀Doo今日登场，待偶慢慢译来：

　　其实大家用windows xp开一个新应用程序时，windows xp会自动创建一个.pf档，.pf档会保存在硬盘内，而你下一次再开同一个应用程序时，速度会增快。

　　而vista的superfetch能力更强，它会自动统计使用者的习惯，而且预测用家会何时开启某些应用程，将应用程的档案预先放入空置的内存空间内，而当你开始那个应用程时，速度会大大增快。

　　上图物理内存中的已缓存一项，就是vista用来放置档的空间。

　　而当一名用家开了一个很大的应用程，如游戏、photoshop等等，windows vista会自动减少已缓存的空间，将那些空间发还给应用程运行。整个过程是全自动，而在windows xp，空置的内存只是空置，系统不会好好利用，而vista就好好改良了，善用多余的内存，提升系统反应，不是盲目占用内存。

Vista之家特别提供英文原文如下：

Windows Vista has a radically different approach to memory management. Check out the "Physical Memory, Free" column in my Task Manager:

At the time this screenshot was taken, this machine had a few instances of IE7 running, plus one remote desktop. I'm hardly doing anything at all, yet I only have 6 megabytes of free physical memory.

Now compare with this screenshot of Windows XP's Task Manager under similar low-load conditions:

Under "Physical Memory, Available" I have approximately 1.5 gigabytes of free physical memory, as you'd expect.

So what's going on here? Why is Vista using so much memory when I'm doing so very little?

To answer that question, you have to consider what your computer's physical memory (RAM) is for. Just as a hypothetical, let's say you wanted to create a new text file: 

1. You double-click on the notepad icon.
2. The Notepad executable loads from disk into memory.
3. Notepad executes.
4. Notepad allocates free memory to store your text document.

So Notepad clearly needs a little memory for itself: enough to execute, and to store the contents of the text document it's displaying. But that's maybe a couple megabytes, at most. If even that. What about the other 2,046 megabytes of system memory?

You have to stop thinking of system memory as a resource and start thinking of it as a a cache.  system memory is yet another type of high-speed cache that sits between your computer and the disk drive.

And the most important rule of cache design is that empty cache memory is wasted cache memory. Empty cache isn't doing you any good. It's expensive, high-speed memory sucking down power for zero benefit. The primary mission in the life of every cache is to populate itself as quickly as possible with the data that's most likely to be needed-- and to consistently deliver a high "hit rate" of needed data retrieved from the cache. Otherwise you're going straight to the hard drive, mister, and if you have to ask how much going to the hard drive will cost you in performance, you can't afford it.