If an HP9000/K200 with 1Gb of RAM and 7Gb of swap starts paging
when avm (active virtual memory) in vmstat hits 2Gb but at the
same time top reports only 400Mb of pages real memory actually
in use, what are the chances that vhand/swapper/unix could be
using signed 32bit arithmatic which causes paging when the total
virtual address space goes from a very large (2^31) byte count
to a very large negative one (-2^31)?
Analysis of the programs being run shows that top is probably
accurate and that 1.6Gb of the avm was never accessed. Despite
this paging starts and does not stop until avm falls below 2^31
bytes. Incidentally, I know that at one system utility (swapinfo)
is doing signed 32bit arithmatic because the output displayed
turns -ve when the reserve for virtual memory passes 2^31 bytes.