[Question & Discorvery] XP Memory Management

[hougtimo]

Hi,

I have a couple of small questions about XP memory management. For this experiment I used two computers:

Computer 1:

AMD Athlon XP 2000+ (1.67GHz)

1024mb RAM

300GB S-ATA

80GB IDE

DVD Re-Writer

Computer 2 (Laptop):

Intel Celeron (600MHz)

192MB Ram

40GB HDD

CD Drive

I installed a full copy of XP Pro on each, and exactly the same programs.

These were:

Ad-Aware Personal

AVG Personal Edition

Zonealarm Pro

Photoshop CS

Avant Browser

CCleaner

Now, the laptop (Computer 2) always seemed to have a bigger % of its ram free than computer 1 did, and also the laptop booted up much quicker aswell (beat computer 1 by about 3 seconds).

Does XP recognise how much RAM you have and optimise itself to that amount of ram? So you would get good performance even on a minimal amount of ram?

Thanks in Advance

HougTimo

[cluberti]

Now, the laptop (Computer 2) always seemed to have a bigger % of its ram free than computer 1 did, and also the laptop booted up much quicker aswell (beat computer 1 by about 3 seconds).

There are quite a few things that go into boot speed, including layout of files on disk, the amount and type of drivers installed, and service dependancies. Laptops with smaller drives (depending on the RPM speed of the drive) generally will boot a trifle faster than a desktop with a large drive for these reasons.

As to the % of memory free, 10% of 192MB is a lot smaller than 10% of 1GB, so this may not be a fair assessment. Windows will swap out more virtual address space to disk on a machine with 192MB of RAM, whereas it will let address space stay in RAM longer before paging it out on a machine with 1GB of RAM. These numbers don't mean anything unless you know why, which I don't think we do. You'd need to get memory dumps of each machine, and do a !vm on each to see how much is in RAM at the time of the dump, and how much has been paged out to disk (and what).

Does XP recognise how much RAM you have and optimise itself to that amount of ram? So you would get good performance even on a minimal amount of ram?

For the most part, yes.

I suggest reading Windows Internals, 4th Edition, for more information on the Windows kernel and memory management - it's the bible on the innards of how Windows works.

[hougtimo]

Hmmm, very interesting indeed. I shall look out for 'Windows Internals, 4th Edition' it sounds worth a good read.

Thanks for all the info

HougTimo