When those sections of memory are needed by their applications, Windows XP retrieves them from the paging file and places them back in RAM. Of course, to do this, Windows XP will most likely need to move other memory sections of other applications from RAM to the paging file.
As you can imagine, this swapping process is continuous when you use several applications at the same time, and it can be a big drag on overall system performance.
Page pooled memory
It’s important to note that Windows XP uses a new virtual memory scheme in which it divides the physical RAM in your system in two sections—page pooled and nonpage pooled. In this scheme, the nonpage-pooled section contains crucial operating system and application files and is never sent to the paging file. Of course, anything in the page-pooled section can be swapped out to the paging file as needed.
Altering virtual memory settings
The Virtual Memory panel displays the size of the current paging file. To make changes to the paging file, click the Change button to display the Virtual Memory dialog box shown in Figure D.
| Figure D |
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| Of all the performance settings, Windows XP gives you most control over virtual memory. |
In the Total Paging File Size For All Drives panel of the Virtual Memory dialog box, the Recommended size for the paging file is based on a formula that multiplies the total amount of physical RAM in your system by 1.5. As you can see on this example system, which has 512 MB of RAM, the Recommended size for the paging file is 766 MB.
Paging file size
Simple math will tell you that this value should be 766 MB, which is indeed the amount being allocated, but due to the way that Windows allocates memory, only 511 MB is actually available to the system. Thus, 766 MB is listed as the recommended size. You’ll also notice that Windows XP specifies a minimum value of 2 MB—Microsoft strongly recommends that you not set the initial size lower than that value.
To improve system performance by adjusting virtual memory settings, you can increase the size of the paging file, or you can move, or spread out, the paging to other physical hard disks.
Increasing the size of the paging file is easy: Simply enter a larger number in the Initial Size text box. Then, double that figure and enter it into the Maximum Size text box. To enable the new paging file, just click the Set button.
The best performance increase will come from moving the paging file from the C drive to another hard disk. Of course, this requires more than one hard disk in the system. Keep in mind that you won’t boost performance by placing the paging file on another drive partition on the same hard disk.
The performance boost from moving the paging file to another hard disk comes from the fact that while one hard disk is handling operating system functions, the other hard disk can simultaneously handle paging file requests. To move the paging file, select the C drive in the Drive list. Then, select the No Paging File option and click Set. Next, select the other hard disk in the Drive list. Then, select the Custom Size option, type the appropriate values in the Initial and Maximum size text boxes, and click Set. When you click OK, you’ll be prompted to restart your system.
Use an old hard disk for your paging file
Finally, if you’re like most IT folks, you probably have a bunch of old hard disks sitting in a box in the back room. These old hard disks aren’t viable for today’s operating system and software disk requirements, but they’re perfect for a paging file. Just add the hard disk to your system as a slave, format it, and configure Windows XP to use it for the paging file.
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