Virtual memory

[InseName]

i always thought that virtual memory is just a space reserved on ur hdd to be used like memory when u don't have enough, assuming that u have enough memory, why is it that some programs need virtual memory to run?

 

[SirOblivious]

i've wondered this myself. If say you got 2gb of ram, why the hell would you run out of memory and have to write to the drive?

 

[bluewall21]

Read this.

 

[SelArom]

Originally posted by: bluewall21
Read this.

That article says

A program instruction on an Intel 386 or later CPU can address up to 4GB of memory, using its full 32 bits

What if you actually HAVE 4GB of RAM? I see mobos that say they can have a max of 4gb ram, so if you had that much ram would you need a page file? if you set the system to use no page file space at all in that case, would you gain any performance?

 

[KillaKilla]

If you have 4 gigs of RAM for non-professional use, you need to be shot summarily.

Really though, the pagefile+RAM size cannot exceed 4GB (Im assuming this has not changes since Win95x32, as I haven't tried since)

 

[Nothinman]

A program instruction on an Intel 386 or later CPU can address up to 4GB of memory, using its full 32 bits

True.

What if you actually HAVE 4GB of RAM?

Then good for you, but it doesn't matter because each process sees 4G of VM and I doubt you have enough memory to allocate 4G per-process.

f you set the system to use no page file space at all in that case, would you gain any performance?

No, infact you'll probably see a decrease in performance.

Really though, the pagefile+RAM size cannot exceed 4GB (Im assuming this has not changes since Win95x32, as I haven't tried since)

That's not true with any decent OS. I believe NT limits you to 4G per-pagefile, but you can have multiple pagefiles.

 

[gamerj]

Programs WILL use your pagefile, but you can minimize it by setting the pagefile to equal sizes both minimal AND maximum...(1500mb or so, assuming you have 1024mb ram, or so ive read)

 

[Nothinman]

Programs WILL use your pagefile, but you can minimize it by setting the pagefile to equal sizes both minimal AND maximum...(1500mb or so, assuming you have 1024mb ram, or so ive read)

Size of the pagefile has no affect on how programs make memory requests.

 

[DJFury]

so if you have 2gb of memory should you or should you not turn off virtual memory?

 

[JBT]

Originally posted by: DJFury
so if you have 2gb of memory should you or should you not turn off virtual memory?

you should NOT turn it off. VM is required by some applications so with out it they are going to be pretty ticked off.

 

[Matthias99]

Originally posted by: SirOblivious
i've wondered this myself. If say you got 2gb of ram, why the hell would you run out of memory and have to write to the drive?

1) Some programs can use up to (or over) 2GB of RAM (at least if the 3GB switch is turned on in a WinNT-based kernel; otherwise, in Windows, you're limited to 2GB per process address space). Photoshop can easily get over 2GB if you work with very large (up in the hundreds of megs when counting all the layers) images, especially while processing filters on said images.

2) Some people, as crazy as it may sound, run more than one program at a time. There's also overhead from the OS that eats up some of your RAM.

With 2+GB of RAM, however, you would be hard-pressed to make a desktop system hit its swapfile very often, unless you were doing things like video encoding or photo editing that required HUGE amounts of memory, and/or multitasking several RAM-hogging programs.

Disabling your pagefile is generally a Very Bad Idea. Some programs just don't like it at all -- although in an ideal world, this situation would not occur. If you keep hitting your swapfile, the solution is more RAM, not no swapfile.

 

[DJFury]

OK thanks. When i hit Ctrl+Alt+Del and check performance it shows PF usage consistently at 1+ gb (I'm assuming this is the virtual memory?) and about 100-200mb of free physical memory, and I already have 1gb installed. I usually have the following running simultaneously:

iTunes
Winamp
MS Money
Outlook
Firefox (w/ 7-10 tabs)
AIM
Virus Protection
Steam for Counterstrike
Limewire
Windows Explorer w/ thousands of songs showing ID3 details (title, author, genre, duration, etc.)
MS Messenger (w/ webcam sometimes)

I don't know if all that justifies a consistent 1.4gb PF usage, but that's what I'm getting so I ordered another GB of memory. I currently have a 3.4ghz P4, hopefully it'll help.

 

[Matthias99]

Originally posted by: DJFury
OK thanks. When i hit Ctrl+Alt+Del and check performance it shows PF usage consistently at 1+ gb (I'm assuming this is the virtual memory?) and about 100-200mb of free physical memory, and I already have 1gb installed. I usually have the following running simultaneously:

iTunes
Winamp
MS Money
Outlook
Firefox (w/ 7-10 tabs)
AIM
Virus Protection
Steam for Counterstrike
Limewire
Windows Explorer w/ thousands of songs showing ID3 details (title, author, genre, duration, etc.)
MS Messenger (w/ webcam sometimes)

I don't know if all that justifies a consistent 1.4gb PF usage, but that's what I'm getting so I ordered another GB of memory. I currently have a 3.4ghz P4, hopefully it'll help.

I'm not sure what you mean by "PF Usage", since there is no value in the Win2K/WinXP Task Manager with that name.

What you really care about is the "Commit Charge" or "Memory Usage" display, which shows how much memory is currently allocated. "Total" is how much is currently in use, "Limit" is how much you can allocate, including pagefile, and "Peak" is the maximum your system has hit since it was last rebooted. The "Physical Memory" display tells you how much of your actual RAM is in use -- if the Commit Charge Total/Peak is greater than your amount of physical RAM, or the Physical Memory "Available" is close to 0, then you need more RAM.

 

[montag451]

Out of interest, how do you do your accounting and play counterstrike at the same time as sending email and surfing.

Wow.
I ain't messing wid you

 

[sangyup81]

Perhaps he runs CS on a Window?

 

[DJFury]

haha well i dont necessarily use all the programs at once, but they ARe running at the same time. Steam for CS is just a program that shows servers/players/maps etc. and is not the actualy game. But i do often alt-tab out of the game to chat or do other stuff between rounds.