Certain product lines of HP minis do aggressive memory checking. On the
HP3000's (I don't know if this is true of the HP9000's) there is a task
which basically soaks up idle CPU time and goes through memory
aggressively testing it all with various bit patterns. If it finds a bad
bit, it marks the entire page as unusable, and spits all sorts of diagnostic
messages out on the console. If I remember correctly, HP calls this feature
'dynamic bad page deallocation'.
Because this task is basically running when the CPU is idle, it has no
cpu impact on the rest of the system.
I would definitely like to see something like this in Linux...
-Dan