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On Monday 13 March 2006 12:31, Jim <Jim@×××××××××××××××××.org> wrote about |
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'Re: [gentoo-user] Mobo/proc combination': |
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> Did you do AMD64 for gentoo or just x86? I just finished getting |
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> everything compiled and setup where I like it. I won't mind doing it |
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> again if running gentoo in 64-bit on an AMD64 would be a noticeable |
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> difference from running 32-bit on an AMD64. |
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|
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My recommendations are: |
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<1G RAM : 32-bit kernel and userland |
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<4G RAM : 64-bit kernel and 32-bit userland |
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else : 64-bit kernel and 64-bit (multilib) userland |
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|
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Rationale: |
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With less than 1G of ram you can still access all of it from any userland |
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process without using the BIGMEM or HUGEMEM options [1]. You could gain a |
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few extra registers from going 64-bit, but that probably doesn't make up |
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for using twice the space for pointers and some other kernel structures. |
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|
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At /exactly/ 1G (or even really close, ~ >768M) you have to go BIGMEM or |
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HUGEMEM to actually get use of all of that memory (in a 32-bit kernel), so |
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I'd go with the 2nd option. |
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|
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With more than 1G but less than 4G you go 64-bit kernel to avoid the BIGMEM |
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or HUGEMEM options, are let your 64-bit hardware to that work. 32-bit |
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userland limits each process to only 4G addressable memory and denies |
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userspace access to the 64-bit only registers, but you don't have 4G |
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anyway and going 64-bit doubles the size of pointers in userspace. |
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|
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At /exactly/ 4G either the 2nd or 3rd option is tenable, but I'd go with |
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the 3rd option is RAM is cheap and you'll probably add more later. |
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Recompiling your entire userland is much more drastic that recompiling |
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your kernel. |
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|
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Above 4G, you also really have a choice between option 2 and 3. I go with |
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3 because I believe that one process should be able to take all my |
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physical memory if it needs it (and I don't ulimit it), particularly in |
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the form of buffers and cache. |
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|
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I simply can't recommend going no-multilib right now. Perhaps in the |
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future that will no longer be the case, but there's just too many things |
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out there that you may want to install as 32-bit right now. |
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|
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-- |
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"If there's one thing we've established over the years, |
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it's that the vast majority of our users don't have the slightest |
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clue what's best for them in terms of package stability." |
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-- Gentoo Developer Ciaran McCreesh |
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-- |
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