More ram?

Discussion in 'other software & services' started by cadmus, Jan 1, 2006.

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  1. cadmus

    cadmus Registered Member

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    I have heard adding ram will always improve performance. A utility called Statbar monitors ram use on my system and rarely shows less than 80-100 MB free. Is this just a result of WinXP memory management, or does it indicate I don't really need more? Not a gamer or heavy number cruncher.
     
  2. pvsurfer

    pvsurfer Registered Member

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    1. Which version of Windows are you running?
    2. What is your current HW configuration, incl. RAM?
    3. Which applications do you run and what do you tend to do most often?

    Happy New Year!
     
  3. cadmus

    cadmus Registered Member

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    Winxp home sp2
    80gb HD
    480 MB Ram
    1.8ghz AMD

    Almost entirely surfin and email. Also a few disributed computing apps. (Einstein@Home.,Folding@Home), both of which are running now, along with fw/av., etc. Statbar shows 283 MB free.
     
  4. WSFuser

    WSFuser Registered Member

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    480mb of ram, i assume ur using 32mb for graphics? neways unless u do heavy multitasking, gaming, or work with extremely large files (like photoshop or video encoding) then u should be fine with ur current memory.
     
  5. pvsurfer

    pvsurfer Registered Member

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    You're not doing much, so you don't need much... Enjoy!
     
  6. cadmus

    cadmus Registered Member

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    Thanks guys.
     
  7. Notok

    Notok Registered Member

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    Well it depends, really.. do you see it going down to 80mb, then suddenly jumping up to 283? It generally won't ever go below 80-100mb, it will page things to disk instead- which you will see as a sudden jump from 80mb free to over half free. The effect of this is that when you open a new program or switch to something that you've had running in the background for a while, it will take longer to open and lag a bit during certain operations as it loads everything back into memory. If you're seeing much of these things happening, it would be recommended that you get more RAM.
     
  8. cadmus

    cadmus Registered Member

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    Ahah! Notok! Thats what I was thinking about Win. memory management, it will swap before exhausting ram. Makes sense, and with memory so cheap these days, perhaps I'll give it a try. Thanks
     
  9. NGRhodes

    NGRhodes Registered Member

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    I think the better way to phrase it would be, windows will not slow down as much if there is the demand from ram (as it can maintain a bigger cache and keep more pages in ram rather than disc).

    Just to exspand on what Notok said, he is correct in stating that windows (nt based) does like to keep a bit of ram free for sudden demand (unless you are daft enough to use a large system cache and it will disc thrash when there is a ram demand).

    Dont forget any windows NT based OS with use free ram (upto 80% in XP if my memory serves correct) for the system cache (for caching file read and write data).

    This could be why your seeing so much memory in use, look at your task manager and see how big your system cache is.

    NT does a good job of resizing its cache when there is paging activity (appilcations loads/saves) and will favour paging memory space to reduce disk thrashing over cache (unless you are daft enough to use a large system cache which I have seen causes the windows to favour the data pages over cache).

    Windows does try to keep a bit of free memory as a reserve for sudden demand eg loading a new app up and loading/saving of a data file, but this does goes down when there is more paging or disc activity.

    And of course this is a fully proportional system where NT tries (and does it very well IMHO) to keep an optimum balance to maintain paging performance (reduce amount of pages swapped to disc) and a decent disc cache size and a little bit of ram in reserve for sudden demand, and this is why you will see free memory usage fluxuate so much, as NT juggles things about.

    You only need enough ram to run all your apps at once, plus a bit extra for cache and spare space, any more and its wasted... just have a look at our test server:

    http://www.rideonby.co.uk/pfuseage.gif

    Edit. I forgot to add, why reduce disc cache and swap pages out to disk and keep some ram spare ?

    Well say you have 100 mb free and you load 200 mb of pages up as a new app + data, you need to get 100mb ram back by reducing the cache (which might not be possible as the data is being loaded and the cache is ALWAYS used, though once loaded can be recovered instantly but might be enough to force swapping out of pages to disk) and as you can guess this is an exspensive process (in disk and memory time), so is best to keep some ram free just incase, imagine it there was NO ram free, thats quite a bit of pages that could well be needed to be written to disc, to free space for the data/apps loading (which always has to go into ram).

    So Windows will always start to swap out unused (it does its best to keep active apps/data in ram if in use) pages of data/apps to disk from ram where it can and also when there is little disc activity it will pull back the system cache with time to it minimum size of 8mb (dont ask me why 8mb though).
     
    Last edited: Jan 3, 2006
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