virtual memory question

Discussion in 'QnA (read only)' started by iMav, Nov 6, 2006.

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  1. iMav

    iMav The Devil's Advocate

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    how much virtual memory shud b alloted to a disk .... i hv all my games installed on another drve so shud i allot it virtual memory and how much .... is the VM related to ram or hdd space or both????
     
  2. Choto Cheeta

    Choto Cheeta Rebooting

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    yup... also in the HDD Speed... if ur HDD is as fast as RAM then u can alot a huge amount..

    The recommended paging file size is equal to 1.5 times the total RAM. (Source)

    but to much page file may slow down ur system... What is your config ??? take a look at this KB from MS http://support.microsoft.com/kb/314482 ...
     
  3. samrulez

    samrulez New Member

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    Well it depends on the ram......yea it should be 1.5 times...of u r physical mem...
     
  4. s18000rpm

    s18000rpm ಠ_ಠ

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    You can Safely Allocate 800MB in your HDD as Virtual Memory.
    if you have only one Hard Disk, then you should keep the Virtual Memory in the OS drive. (do not put it in other partition).

    But if you have more than one Hard Disk, then you can put the Virtual Memory in the Other(non OS) Hard Disk Drive. this actually speeds up the performance, when compared with VM in OS HDD.

    If your PC has 1GB of more of RAM, then 500MB-700MB VM should be enough.
    If you use programs such as Photo Shop, then you have to allocate 1GB of VM.

    NOTE: Always set the Minimum & Maximum VM value as same,.
    (e.g. Min.=500MB & Max. =500MB)

    a useful site about Virtual Memory & its Tweaks TechARP

    VM in separate, dedicated partition
     
    Last edited: Nov 6, 2006
  5. OP
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    iMav

    iMav The Devil's Advocate

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    my config ....

    p4 3ghz
    512mb ram
    160 non-sata hdd

    currently .... max size1536
    min size - 768

    it quiet frequently givs me VM low error
    __________
    cant 2 partitions of same hdd hv VM?
     
    Last edited: Nov 6, 2006
  6. s18000rpm

    s18000rpm ಠ_ಠ

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    set both Min. & max to 1GB (my opinion->800MB).

    as you have only one Hard Disk, then allocate the VM in OS partition, or if you can create a new partition of 1GB, then put it in it.

    read the "VM in separate, dedicated partition" i've posted above.
     
  7. OP
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    iMav

    iMav The Devil's Advocate

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    1.5 times of 512 comes out to b 768 which is currently the min size does setting both sizes same hv any affect on the performance
     
  8. s18000rpm

    s18000rpm ಠ_ಠ

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    yes. it will improve the performance, as now the OS doesnt need to Resize the VM every now & then.
     
  9. mediator

    mediator New Member

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    @mav3 : Instead of VM, remove all the unnecessary startups that consume ur RAM! That will reduce the frequency of VM low errors! Then u can think about VM!

    @saruav_cheeeta : Hdds are not fast as RAM. Cache memory is the fastest, followed by RAM and then hdd!
     
  10. Third Eye

    Third Eye gooby pls

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    @mav3: Just increase the virtual memory equally i.e 1500-1500.

    More you increase virtual will take more disk space (i.e If increase to 1500MB will take 1500 MB Disk Space)
     
  11. OP
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    iMav

    iMav The Devil's Advocate

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    @tech mastermind then y is RAM related to VM??? in that case i can assign the 15gb of my games drive which is free as VM
     
  12. mediator

    mediator New Member

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    @mav3 : If u wanna learn the whole concept of Virtual memory, then I suggest u read "Operating Systems by Galvin".

    To make u understand in short : Cache memory is the fastest memory that is used to store page tables, RAm is slower than cache memory and holds the applications environment,processes etc. Hardisk is slower than RAM. Now when u keep opening applications u open a lotta processes. These processes need memory to work! Now suppose ur RAM size is 64 MB and u opened winamp,3 internet explorer pages, a chess program etc which need a total 70 MB memory to work. U keep listening to winamp and work on one IE page for sometime. Under these conditions since ur memory usage is exceeding 64 MB, its essential to have Virtual Memory. Now pagefile or swap file is nothing but some space on hardisk allocated by OS that fools the programs that u have more than enough RAm to work! When u work as highlighted above, the chess program and 2 IE pages go to background and become part of the virtual memory and reside in the hardisk swap u allocated. When u switch from one IE page to other, the IE page from pagefile is swappedand brought under active working and the active one goes to pagefile. Hence the term "swap file"!

    So this is the simple concept of pagefile or swap file! Virtual memory = RAM memory + pagefile size! U must have noticed, that when the system is heavily loaded and winamp is ON, there are pauses felt in the song. When u relieve the system of the load then everything works fine. Thats coz all the processes in the heavily loaded system demand for active working then, and need to be executed in the RAM memory. Since the RAM is limited, the processes are "scheduled" to be executed via various scheduling algorithms! So the winamp process is scheduled, executed and scheduled again to be executed. Since there are many active processes executing one by one, the time delay between the winamp process executions become large because of which u experience pauses!

    I hope the concept is somewat clear to u!
    Thats why it is much better to increase RAM than increasing Virtual memory size by increasing pafgefile size! If u encounter low memory screens, then remove the unwanted and useless startup programs (processes) or increase ur RAm or increase ur pagefile size!

    But since hdd are much slower than RAM u'll experience a great degradation in performance by increasing VM! WHich one do u find fast XP on 64 MB RAM or XP on 512 MB RAM??

    I hope u got mah point!
     
    Last edited: Nov 7, 2006
  13. Ramakrishnan

    Ramakrishnan The Researcher

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    playing around with virtual memory settings can seriously impede the smooth performance of your PC. Generally one should let windows manage it.
     
  14. janitha

    janitha New Member

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    For the last three months, ie. ever since I got 2GB Ram, I have disabled VM entirely. Of course, I don't game or use programs like photoshop. When I do use things like video editing (rarely), I do enable it. No problem ever since.
     
  15. Cool Buddy

    Cool Buddy Active Member

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    Alloting too much space as virtual memory will beat its whole purpose. If you have 512 MB of RAM, you should allocate around 1GB for page files. You may consider this example, "Since the HDD is not as fast as RAM, Windows will forever keep searching for data in page file and hence it will be of no use".

    The minimum and maximum sizes needs to be same because if they are not the same, windows will keep changing its size now and then and this will slow down your PC
     
  16. OP
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    iMav

    iMav The Devil's Advocate

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    thanx mediator .... 1 of my profs also told me the same thing today
     
  17. koolbluez

    koolbluez Šupər♂ - 超人

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    Yah... bub... 1.5xRAM is the say...

    You can do it in 3 main ways:
    1. Set the virtual memory to System Managed size
    2. But then, there is extra work done by the processor. Every time u work on a file, it calculates the ram required, which is a performance hinder. So u can set the size urselves to initial min size of 0 (or 2mb, which is min in XP) and max to 1.5 to 2 times ur standard RAM, can go upto 1GB, if u have enuf space.
    3. But then, the earlier bottleneck of the system calculating RAM required is not yet curbed, as still it checks within the 2 mb-1.5x mb limit. So some people put the max and min virtual RAM the same, as calculations on part of system for recommended VRAM size is negated.

    It's up to u, but if u've low space resources, better use method 2 (min 2mb, max 1.5x of RAM) or method 3 (if u have oodles of it)

    Also make virtual RAM only for the drive having ur Windows files (default C drive in mono-boot systems)
     
  18. OP
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    iMav

    iMav The Devil's Advocate

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    ^^ thanx
     
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