Module Name:	src
Committed By:	chs
Date:		Fri Mar 26 17:33:31 UTC 1999

Modified Files:
	src/sys/uvm: uvm_pdaemon.c
Log Message:
add uvmexp.swpgonly and use it to detect out-of-swap conditions.

numerous pagedaemon improvements were needed to make this useful:
- don't bother waking up procs waiting for memory if there's none to be had.
- start 4 times as many pageouts as we need free pages.
this should reduce latency in low-memory situations.
- in inactive scanning, if we find dirty swap-backed pages when swap space
is full of non-resident pages, reactivate some number of these to flush
less active pages to the inactive queue so we can consider paging them out.
this replaces the previous scheme of inactivating pages beyond the
inactive target when we failed to free anything during inactive scanning.
- during both active and inactive scanning, free any swap resources from
dirty swap-backed pages if swap space is full.  this allows other pages
be paged out into that swap space.