Memory Management - HP-UX


vhand and swapper daemons control paging and swapping.

Notes on memory management

Thrashing - paging and swapping at such a high level, virtually no processing taking place.

File system swap is slower than device swap because it writes in smaller blocks ( so more writes required) and may not be in contiguous blocks

swap must be big enough to hold all shared memory + shared libs + stack + data for the largest executable process. To calculate this, can use: size command to calculate program requirements. ipcs to display shared memory (ipcs -m -a). swap should be an integer of 2Mb (because swapchunks use 2Mb chunks). As a rough guide, a swap size of between 2 to 4 times the memory size is recommended.