Thus spake Vallo Kallaste <[EMAIL PROTECTED]>:
> Userspace processes will allocate memory
> from UVA space and can grow over 1GB of size if needed by swapping.
> You can certainly have more than one over-1GB process going on at
> the same time, but swapping will constrain your performance.

It isn't a performance constraint.  32-bit architectures have 32-bit
pointers, so in the absence of segmentation tricks, a virtual address
space can only contain 2^32 = 4G locations.  If the kernel gets 3 GB
of that, the maximum amount of memory that any individual user process
can use is 1 GB.  If you had, say, 4 GB of physical memory, a single
user process could not use it all.  Swap increases the total amount of
memory that *all* processes can allocate by pushing some of the pages
out of RAM and onto the disk, but it doesn't increase the total amount
of memory that a single process can address.

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