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Apart from using up too much disk space, how much swap space can you allocate before it will degrade performance or cause problems on an x64 OS? What differences are there between the x64 OSes? I'm not talking used swap space, just telling the OS use x much for swap.

I get sick of the problems associated with dynamically changing the swap size, and I don't want to run out. Plus I'm the type of user who has a lot of things open simultaneously even if they are large programs, eg. right now I have 12 chrome windows probably averaging 10 tabs per window, plus my other running programs including firefox.

Edit: Maximums allocated with no performance loss or errors so far

  • RAM Multiplier: 4x Unknown OS
  • Maximum GB: 128 GB Unknown OS
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No amount of swap space is too much, although I wouldn't go over 4 times RAM. They recommend 2 times RAM, but as I had already used that and found it wanting, I used 4 times RAM as the sizing for swap on my machine with 32GB of RAM which resulted in a swap space of 128GB. So far I have seen no need to increase it.

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    I disagree. An OS will need to keep track to remember which part of swap is in use. That will cost some memory. This should not cause problems in most cases, but if you have a low memory host and huge swap then it can degrade performance. (E.g. a 32 MB computers and a few TB of swap). This is why I disagree with your opening sentence "No amount of swap space is too much". Up to 4x main RAM should be fine though, – Hennes Jan 31 '14 at 6:39
  • The memory used for bookkeeping need not be proportional to the amount of swap space, it can be constant with more memory only making possible to keep more of the swap space availability map in memory making searching for free space faster. – Dan D. Jan 31 '14 at 6:49
  • @DanD. "need not be proportional to the amount of swap space" but is it? and on which OSes? – BeowulfNode42 Jan 31 '14 at 7:19
  • @DanD. What OSes have you run with the 4x and which OSes with 128GB? – BeowulfNode42 Feb 2 '14 at 23:47
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Having 2gb,4gb,8gb, or more will not degrade performance. Using it will.

Your memory is 2000mb/s or higher, and your swap file is 60-100mb/s (unless you have a ssd). Anytime you depend on your swap file because you ran out of real memory slows down whatever programs are using it.

If you have 8gb or more windows will swap small amounts out over time and it won't affect performance. However, if you have 8gb of RAM and a program need 16gb now half of your RAM is in the slow lane and that program will run slower because of it. At 2+ times over the limit windows will constantly be trying to swap things in and out of memory and everything will be slow.

  • Your point about when the OS is using more than 2 times the amount of RAM in its swap space will usually result in a slow system anyway, may be true most of the time, it is not the question I was asking. – BeowulfNode42 Feb 2 '14 at 23:46
  • @BeowulfNode42 No amount of swap space will cause windows to malfunction. If you have more than 2x-4x swap file vs RAM most of your swap file will go unused (and be unnecessary) unless you have a RAM greedy program. As soon as you write to the swap file the speed drops from 2000+mb/s to approx 60-100mb/s. The program that is using a lot of RAM will slow to a crawl and windows performance will also be affected. In the days when 512mb of RAM was common scanning at 600dpi was a nightmare and often took 30min to save the file because windows was using so much swap file. – cybernard Feb 3 '14 at 0:31

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