Increasing swap limits
Sat, 28 Sep 96 17:11 EDT

I have just recently received two Pentium Pro 200's with 128M of RAM in
each. I am trying to run a very large simulator application with
Electric Fence linked in to check for bugs. The simulator alone comes
close to exceeding the limits of Linux's swap capabilities. With
Electric Fence linked in, it takes well over 1 Gig of virtual memory.

I would like to go out and buy a 2G disk and throw it in as a dedicated
swap drive. However, from the docs and what I can understand in the
source, Linux can only handle 1G of swap made up of a maximum of 8
swapfiles or partitions of a maximum of 128M apiece.

It looks like all I have to do to increase the maximum number of swap
areas is to change MAX_SWAPFILES in the kernel source. But I would also
like to be able to use larger partitions. To do that it looks like I
will have to change the swapfile format from a one-page map to a
multi-page map. Is it this simple, or are there other non-obvious
factors that limit the maximum swap size? If I understand correctly,
each process is limited to 3G of address space because of the way the
kernel space is mapped in, but shouldn't we be able to have much more
swap total?

Gene McCulley