swap on x86 with 4GB RAM?

[wazow]

I am going to install Gentoo on an x86 machine with 4GB RAM. Will the swap partition be used in such setup? (Is there any addressing space left to use it?)

[nunne]

I don't think you will need any swap space.. it feels like swap-space is a thing of the past but then again.. it all depends on what your going to use it for.... like compiling or creating really big artworks/3d etc might put you in the need for swap.. but I have almost never used my swap partition, and I only have 512mb of ram.
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>>touch /dev/null

[ewan.paton]

very doubtful, i have a gig and dont use swap but i would learn how to create a swap file in a directory for emergences, i cant rember at the moment also remeber to enable highmemory in the kernel

it probably only matters if you have a very big database
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[wazow]

I am not really wondering if I will need swap. This is a question of relatively little importance.

I am searching for someone who knows the kernel implementation well enough to say, that kernel can handle memory beyond 4GB (provided that the remaining part is swapped out).

If it happens so that kernel cannot handle swaps with 4GB RAM installed, then the first question (wether swap is needed) does not have to be answered at all...


All this on 32bit x86 obiously.

[EDIT]Though this is not really the topic of this thread I though would admit that this server will run processes which *will* exhaust 4GB for sure [/EDIT]

[ewan.paton]

the high memory options are 4 and 12 gigs but there are systems out there running linux on terabytes of ram, i think theres a problem wit the x86 32 bit arcutecture addressing more than 800 odd megs for a single lowlevel process but i never realy understood it and its a physical hardware limitation nothing to do with linux

out of interest what are you doing, high end simulations or database stuff
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[wazow]

This will be model-checking and SAT solving. I guess model-checking could be classified as high-end simulation.

[Carnildo]

On an IA-32 x86 system, the CPU can handle up to 32GB of RAM, with a limit: no one process can use more than 4GB. So if you've got a 28GB swapfile, Linux should be able to give you 32GB of usable memory.

If you need a single process to access more than 4GB, you'll need an Itanium, Opteron, or other 64-bit system.

[mattst88]

Straight out, yes the kernel will support 4G of RAM.