Re: Large memory question

Ingo Molnar (mingo@chiara.csoma.elte.hu)
Mon, 29 Nov 1999 16:13:22 +0100 (CET)


On Mon, 29 Nov 1999, Jakub Jelinek wrote:

> You can already have 8Gb of swap space in a box with 1Gb RAM.
> Say on ia32 you have at most 8 swap partition/files, at most 2Gb each,
> that's 16Gb, right?

oops, right. The swap offset (the pfn of the swap-page) was encoded as-is
into the pte's higher 24 bits even in 2.2, this gives a limit of 64GB
swapspace on 32-bit platforms with 32-bit ptes. PAE mode raises this limit
to 16TB, as there are 32 bits worth of pfn encoded in the upper 56 bits of
the 64-bit pte.

-- mingo

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