virtual memory

[tophatter]

This has happened to me a couple of times. A get a little exclamation box saying that my virtual memory minimum is too low and windows is increasing my paging size.

It has not affected what im doing but i am just interested why it is doing it. I have checked my hard drive and im only using 8GB out 0f 40 so i have loads of space on Hard drive

[MattR]

TH, I'd help only I have virtual amnesia! :D Not sure what's causing that, don't know about XP, haven't had cause to look, but I seem to remember on windows98 there was somewhere you could adjust virtual memory.

[tophatter]

i think it is doing that automatically Matt, and is just telling me it is doing it. I just wondered what it was

[MattR]

Ok, check in control panel/systems/(advanced tab) see if let windows control my virtual memory is checked. Maybe it isn't??

[tophatter]

it has let windows choose what is best for my system as the option that is checked. Like i say i think it has done that off its own back but im puzzled as to why it was low on whatever virtual memory is

[MarcusMel]

For windows XP

Control panel
system
advanced
performance box clicking on setings button.
advanced tab
Virtual memory click on change button
Use either the system managed size or
use the custom size of 400 to 800 MB

[MarcusMel]

was told by betfair helpdesk to use 300MB on the internet which may have something to do with it.

[tophatter]

cheers Marcus and Matt.

[MarcusMel]

For those who wonder what virtual memory is:- its fixed space aloted to your harddrive which gets used as computer memory(RAM) as you never have enough memory to run windows.

[plater]

I recently upgraded a PC for my neighbours son, when I fired it up it took 10 mins to get the Screen up, in this time the HDD was going ten to the dozen, my first thoughts was virus Etc, when I had a look he had Loaded XP PRO on a 64Mb Machine:yikes: , to cut a long story short, I put in another 256Mb Ram got rid of 998 Virused files, and 97 Trojans Et Al.

It now runs sweet as a nut, so if anyone has their HDD going ten to the dozen everytime they click on something, then Virtual Memory is probably being Accessed, as Marcus say's you can never have enough RAM.

Plater

[bigcumba]

Amazing how naive some folk can be when it comes to their expensive computers! I had to fix a colleagues home PC last week - it was running extremely slowly and wouldn't run at anything other than 640x480 resolution. Question - do you have up to date virus software - don't know, next question, do you have a firewall installed... what's that? I did a system restore to a month back, just to get it running properly to start with. They have a broadband connection, so you can imagine the mess they were in. Got them Norton AV and ZOne Alarm installed - Norton reported 49 viruses, and I installed a few spyware killers, knocked out literally thousands of nasties, including premium rate diallers etc.... once back up and running had to remove system restore, run the AV again to finish it's job, then re-start the system restore. All seems fine now, but what a lot of hassle that could have been avoided!

[bennettp23]

I'm a 3rd year Computer Science student, I'm crap at explaining stuff, but here goes....


Virtual memory is used to enable many large programs to share the CPU and memeory resources of the system. It allows each program to use the memory space as if it is the only program running on the computer. Each program thinks that its memory allocation starts at 0, this makes for easier programming, when a program wants data form memory the operating system or the Memory Management Unit then 'maps' each the virtual address from the program say '00100' to the physical address where the data really is stored say '01000'.

Paging is used to expand the memory available, as Marcus says, the hard drive is used as an extention to main memory. All available memory (main memory and hard disk space) is split into equal managable chunks called pages. At any one time some 'pages' are in main memory with the rest being stored on the hard disk. Now when a process (program) wants to access memory as described above but the piece of memory it wants is not held in main memory but on the disk the operating system must swap the data from disk to main memory so it can be accessed, paging helps to do this by being able to swap any page in main memory with any page on disk because they are always of equal size.

The result of all this is that each program does not have to worry about sharing memory with any other program and many programs can run at the same time. (well not really at the same time, each takes its turn on the CPU, but to us it looks like the same time)

I could go on and on and deeper and deeper.......

but I can feel all the eyes glazing over......

[MarcusMel]

Cheers Bennettp23 - Nice to see your paying attention to what your being taught :D

[bigcumba]

zzzzzzz....

Only joking, good explanation mate! :)