Module Name:	src
Committed By:	thorpej
Date:		Wed Mar 31 23:23:48 UTC 1999

Modified Files:
	src/sys/sys: pool.h
	src/sys/kern: subr_pool.c
Log Message:
Yet more fixes to the pool allocator:

- Protect userspace from unnecessary header inclusions (as noted on
current-users).

- Some const poisioning.

- GREATLY simplify the locking protocol, and fix potential deadlock
scenarios.  In particular, assume that the back-end page allocator
provides its own locking mechanism (this is currently true for all
such allocators in the NetBSD kernel).  Doing so allows us to simply
use one spin lock for serialized access to all r/w members of the pool
descriptor.  The spin lock is released before calling the back-end
allocator, and re-acquired upon return from it.

- Fix a problem in pr_rmpage() where a data structure was referenced
after it was freed.

- Minor tweak to page manaement.  Migrate both idle and empty pages
to the end of the page list.  As soon as a page becomes un-empty
(by a pool_put()), place it at the head of the page list, and set
curpage to point to it.  This reduces fragmentation as well as the
time required to find a non-empty page as soon as curpage becomes
empty again.

- Use mono_time throughout, and protect access to it w/ splclock().

- In pool_reclaim(), if freeing an idle page would reduce the number
of allocatable items to below the low water mark, don't.