Page File?

[Shantanu]

Usually when I get a new computer or reformat, the first thing I do in Windows is to turn off the page file, defragment, then create a new page file 2.5 times the size of my RAM. This is so that it's one piece and sits at the front of the hard drive.

But how necessary is it really to do this? How much benefit do you get, vs. just letting Windows manage it?

I'm soon getting a new computer with 1GB of RAM, and I was wondering if it was really necessary to make a 2.5GB page file.

 

[ExplodingTurnip]

Not really. My desktop box has a gig of RAM and I use a fixed pagefile that's only 400MB. I've had no noticeable performance hits and the system never complains about running out of virtual memory, even when running HL2 and Doom3.

This pagefile guide (rojakpot.com) offers some excellent tips on how to optimize your pagefile.

 

[djnes]

I'm soon getting a new computer with 1GB of RAM, and I was wondering if it was really necessary to make a 2.5GB page file.

We can't tell you what to set the page file as. You need to determine it my using your task manager to monitor your peak usage. In this day and age, 2.5 times system RAM is overkill for most people. I have 2 GB of physical RAM and I have a 1 GB static pagefile.

Also, just because you recreate the swap file, doesn't mean it's placed at the beginning of the disk...just an FYI. My suggestion would be to read the sticky so you know how to monitor your usage, and then make your decision based on that.

 

[sirius]

Here's a good link on Virtual Memory
http://aumha.org/win5/a/xpvm.php

 

[KoolDrew]

First, moving the pagefile to the front of the drive does not help performance at all. The outer cylinder will only make a difference when transfering long buffers. Pagefile IO is never in buffers larger then 64KB at a time and there will be many paging and non-paging IO's to other files in the process. Thus, seek time completely dominates the IO time.

For the same reason, unless it gets to an extreme point, you don't need to worry about fragmentation. Most I/O access is random not sequential, meaning sequentialness matters very little. If I read block 1 and then block 20 it will not matter one bit if the file is sequential or not, I will have to seek anyway. Most I/O is of that nature. The biggest major exception on a modern system being large data files.

To determine the optimal size of the pagefile you should run your most intensive applications for a while and then measure your PF usage using the "%usage" counter in perfmon. The pagefiles initial size should be set to at least four times the observed usage, while the maximum should be set to at least twice that.

The only way to measure pagefile usage with tools built into Windows is through perfmon, so that is what you need to use. However, if you do insist on using task manager the initial size should be set to 2x what the "PF Usage" graph says. Set the max to at least twice that.

My desktop box has a gig of RAM and I use a fixed pagefile that's only 400MB.

The only time the pagefile should be set as a fixed size is if it is in a partition of its own. However, even that is a bad idea as it would increase your average seeking distance, thus it will decrease performance.

This pagefile guide (rojakpot.com) offers some excellent tips on how to optimize your pagefile.

I definitely would not call it "excellent." The first two paragraphs under "How Does It Work?" are completely wrong:

Virtual memory is created using a special file called a swapfile or paging file. Whenever the operating system has enough memory, it doesn't usually use virtual memory.

The term virtual memory includes several different mechanisms. Paging is only one of these mechanisms, and the pagefile is only one of the many files involved with paging. Also virtual memory is always in use with modern operating systems.

 

[XOR != OR]

Regarding performance: If you want to increase performance of the page file, stick it on a seperate harddrive, perferrably on it's own channel.

 

[KoolDrew]

Regarding performance: If you want to increase performance of the page file, stick it on a seperate harddrive, perferrably on it's own channel.

Exactly. If you have one drive you want the pagefile in the same partition as your OS and applications. If you have more then one you want it in the most-used partition on your least-used hard drive.