p_nice, and scheduling - (nf)

[bob at ucla-locus]

From:            Bob English <bob at ucla-locus>

I suspect that nice works fine as long as you have sufficient
real memory to prevent excessive swapping.  On systems where
memory is scarce, not only doesn't it help, it promotes
thrashing.  The scenario runs like this:

1) A large, niced program doesn't run for a while, and gets swapped
	out.
2) The scheduler notices that nobody's running (it only takes a
	moment), and decides to swap the program back in.
3) Once in, the program gets pre-empted and swapped back out.

That's wha happened on our 11/45 under v7, anyway.

--bob--