physical/virtual memory question....

Discussion in 'Windows Desktop Systems' started by U2Penn, Dec 5, 2002.

  1. U2Penn

    U2Penn U2Penn

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    on my system my total physical memory is 512 megs with 254 megs available. total virtual memory is 1.72 gig with 1.23 gig available + page file space is 1.22 gig. now the page file space is the place on my hard drive to store memory, right? does it only story memory on my page file when u run out of physical memory, right? plus, virtual memory is the combination of page file and total physical memory, right?

    thanks in advance.
     
  2. Perris Calderon

    Perris Calderon Moderator Staff Member Political User

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    u2...there are lots of htreads concerning the pagefile, and virtual memory...lots of fun reading if you want to do a search.

    the pagefile is basically a big storage container, which is mostly empty, but it iss always available to put information if you are ever in need of more ram then you have installed.

    here's an interesting fact...without the pagefile taking addresses for ram which is asked for but never accessed, you would need a coupla gigs of ram to keep running

    some people argue that the concept "virtual memory"involves all the backing stores, backup files plus the actual memory installed.

    others will argue that virtual memory does not include acual ram.

    no matter.

    simply out, for most users, let xp manage the pagefile, and you can't go wrong.

    for power users, you should increase the initial minimum to 2x ram or more depending on your needs, and leave the maximum system managed
     
  3. dave holbon

    dave holbon Moderator

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    You can go wrong if you don't undestand how the swapfile works especially if you have a small hard drive and 2gig of ram.
     
  4. Perris Calderon

    Perris Calderon Moderator Staff Member Political User

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    as usual dave, you are correct...(I hate when I'm corrected)

    but, to take this a little further...xp will actually downsize the pagefile if you are short on hardrive space, and it will actually try to get by on as small a pagefile as possible

    this is only if you let the system manage the memory in it's entirety...obviously, if you set the initial minimum, the os will not make a pagefile smaller then your set initial minimum

    now, you are correct, if the system has just enough hardrive space to think it can allot a sufficient pagefile, but your intentions are to use alot of this space immediately.

    in this case, you would suffer a slow down when the os deminished the size of the pf to fit the hardrive restrictions
     
  5. dreamliner77

    dreamliner77 The Analog Kid

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    How many people will have 2 gig of ram and a harddrive so small as to not be able to have an adequte pagefile?
     
  6. U2Penn

    U2Penn U2Penn

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    thanks for the info :) i was a little confused because i thought the page file was supose to be completely empty UNTIL the physical memory was full....then spilled into the page file. the numbers didn't add up right because there was a little bit of space used up in my page file.
     
  7. Perris Calderon

    Perris Calderon Moderator Staff Member Political User

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    u2...your pagefile is almost empty until you are near out of ram

    the activity before is like priming a hose before you need to water the lawn...it's one of the things that speed xp

    what you see in your monitor is pagefile activity...it is not pagefile use...if you want to see just how much is actually in the pagefile, download the zip that I post here
     
  8. U2Penn

    U2Penn U2Penn

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    Dealer,

    i downloaded the zip and this is what came up for me:
    current page usage 87 mb
    session peak usage 114mb
    current page file size 768mb
     
  9. Perris Calderon

    Perris Calderon Moderator Staff Member Political User

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    now, if you look at perfmon, you will see a couple of hundred mbs of pagefile in use, even though you have less then 100 mbs written

    the extra mbs of the pf useage is potential.

    now, of the ram that's actually written...most of that information is in both...pf and the ram it came from.

    until of course, the ram it came from is claimed by another process.

    very efficient

    your pf size needs to reflect the amount of ram you actually have, so it can be ready with the potential use.

    it doesn't need to be the size it actually uses...that will slow you down.

    this is why the more ram you have the bigger the pf needs to be, not the smaller.

    any, good to meet you.

    gone for the day
     
  10. gothic

    gothic LinuXPert

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    I have one or two 'forensic' type utilties, one of which is able to decode certain areas of the pagefile.sys. There are certain datii that are automatically written there in preference to RAM (i.e. explorer history/typed URLs etc) which can easily be accessed using such freely available utilities. Takes a little time, mind...depends on the size of the pagefile!!

    TOK
     
  11. B~B

    B~B Guest

    Thanks for the explanation.

    :)
     
  12. Zedric

    Zedric NTFS Guru Folding Team

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    Windows will swap mamory out to the page file even if you're not out of RAM. This is because if you suddenly need alot of RAM, Windows won't have to swap other stuff out first. It can just claim the space.
     
  13. Perris Calderon

    Perris Calderon Moderator Staff Member Political User

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    xp doesn't do a swap in the situation you're talking about zedrick

    it will write to the pagefile before you're out of ram, but it also keeps that code in physical in memory at the same time and it stays there untill it's claimed

    this is the sweetest part of the xp memory management
     
  14. Zedric

    Zedric NTFS Guru Folding Team

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    I know. I didn't say it did or didn't because you allready had. Maybe I was too vague. :)

    Deleting the data from RAM would make the method pretty useless. :)
     
  15. Perris Calderon

    Perris Calderon Moderator Staff Member Political User

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    Deleting the data from RAM would make the method pretty useless.

    well said

    jeeze...it tales me a whole thread to say what yoiu just said in a sentence

    ah me