Important opinions concernig virtual memory

[titomax82]

Hi all guys,
this is my first post - hoping I used the correct forum's section -
Sorry for my language, I'm italian... and I'm a fan of this site.
I have some question about the Virtual Memory Chapter specifically for "WIndows XP".

As the guide says, to determine the total memory needed (real + virtual), I should watch to the peak I reach with the maximum ram requiring program I use, or the maximum ram requiring situation. That's clear. Supposing I have 2GB of physical ram and my maximum demanding application doesn't need all of this ram (even considering windows background ram utilization), "in theory", I should not need paging memory. But as suggested, and as I noticed in my experience, some programs need paging memory to work, even if there isn't a real need or usage (I noticed this especially with some games).

So in my situation, for example, I don't really need paging memory, but I must enable it to make program run correctly, just to make it run.... so, it's only a question of compatibility. Supposing ram is much faster than hdd pagedfile, I could use a ramdisk to allocate pagefile, so if the "remaing" physical memory is all used (total physical - ramdisk), windows can swap to the ramdisk and it should be as fast as normal memory. This always considering that the ram needed in my situation does never exceed my 2GB so I don't go out of ram.

Even if the program pages something just because it has to do so, for how it's been programmed, I shouldn't notice performance impact because it pages to ram!

This reasonment should be correct: ram is enough, and pagefile is enabled, but not for more ram, but only because some programs requires its presence... so there are 2 important question:
- in this particular case should I however enable the "disablepagingexecutive" tweak or in this case it's useless and I leave it to 0 because paging, in this particular circumstance is useful?
- considering common programs or games that need pagingfile which is the minimum size I should use (for example some games doesn't run with 512mb, but with 768 they do). Have I to try different ramdisk pagefile all the times or you can suggest a minimum? 768 could be right? or I could use something less? (I never went out of ram with this pagefile in the past even with 1gb of physical ram, now are 2gb)

Hoping I have been clear and you can help me!
Greetings
Tito

[jasperchc]

hmm... not quite sure about you disabling VM, but if you wanna keep it at min, i think you should just let your system manage the size for you.

[titomax82]

having the pagefile to a ramdisk I must specify a fixed size...

[jasperchc]

ahh, dont know about that , i guess you need someone more knowledgable to help you

[Adrian Wong]

You can enable disablepagingexecutive to force Windows to use more of your physical RAM. But many programs still require the page file to work. In any case, even if you disable the page file, Windows will still create it whenever it needs more RAM. So, it makes sense to pre-create the paging file so you can ensure that it's contiguous.

As for the smallest size you should set, as explained in the article, the best thing to do would be to try out your system with as many of your applications running together (in the worst case scenario) and check the paging file usage. Then round it up (for example, if your paging file reaches 1.3GB, round it up to 1.5GB) and use that number for your permanent paging file.

Don't worry so much about making the smallest paging file you can. Hard drive space isn't as critical as it was in the past. Now, you can add an extra 500MB to your paging file without feeling the pinch.

[Adrian Wong]

Originally Posted by titomax82

having the pagefile to a ramdisk I must specify a fixed size...

Err.. I think I addressed the issue of placing a paging file on a RAM disk. It's pointless, like reaching behind your head to touch your nose.

[peaz]

The best would be to purchase a second physical hard disk, partition a 1GB partition and dedicate that 1st partition to the swap file. That's what I do, except mine is a 2GB partition. With XP, you can easily disable the low disk space notification (since that partition will have like a couple of MB of free space, windows won't allow you to use the whole partition for swap file) . But for VIsta, you'd have to live with the darn nag everytime you boot vista.

[Adrian Wong]

IMHO, it would be best to place a page file on every hard drive you have (with separate channels, of course). Windows will be able to switch from drive to drive, according to usage patterns for maximum performance.

Hmm.. Time to update the guide again, I think.

[peaz]

Originally Posted by Adrian Wong

IMHO, it would be best to place a page file on every hard drive you have (with separate channels, of course). Windows will be able to switch from drive to drive, according to usage patterns for maximum performance.

Hmm.. Time to update the guide again, I think.

Hmm Windows's that advanced already? Hmmmm. Darn.
Anyways, i basically put mine at the same hard disk I use for backups.

Hmm as for seperate channels, you should be safe if you're on SATA drives right?

[Adrian Wong]

Originally Posted by peaz

Hmm Windows's that advanced already? Hmmmm. Darn.
Anyways, i basically put mine at the same hard disk I use for backups.

Hmm as for seperate channels, you should be safe if you're on SATA drives right?

Yup, Windows XP and Vista will automatically switch to the paging file of any drive that is not busy.

Yeah, SATA drives all have separate channels.