kmem_cache hardening and performance improvements

- Added slab work queue task which gradually ages and free's slabs
  from the cache which have not been used recently.
- Optimized slab packing algorithm to ensure each slab contains the
  maximum number of objects without create to large a slab.
- Fix deadlock, we can never call kv_free() under the skc_lock.  We
  now unlink the objects and slabs from the cache itself and attach
  them to a private work list.  The contents of the list are then
  subsequently freed outside the spin lock.
- Move magazine create/destroy operation on to local cpu.
- Further performace optimizations by minimize the usage of the large
  per-cache skc_lock.  This includes the addition of KMC_BIT_REAPING
  bit mask which is used to prevent concurrent reaping, and to defer
  new slab creation when reaping is occuring.
- Add KMC_BIT_DESTROYING bit mask which is set when the cache is being
  destroyed, this is used to catch any task accessing the cache while
  it is being destroyed.
- Add comments to all the functions and additional comments to try
  and make everything as clear as possible.
- Major cleanup and additions to the SPLAT kmem tests to more
  rigerously stress the cache implementation and look for any problems.
  This includes correctness and performance tests.
- Updated portable work queue interfaces

1 files changed, 1 insertions, 2 deletions

diff --git a/include/sys/vmsystm.h b/include/sys/vmsystm.h
index e92c17bdd..1cb716f13 100644
--- a/include/sys/vmsystm.h
+++ b/include/sys/vmsystm.h
@@ -35,8 +35,7 @@
 extern vmem_t *zio_alloc_arena;		/* arena for zio caches */
 
 #define physmem				num_physpages
-#define freemem				nr_free_pages() // Expensive on linux,
-							// cheap on solaris
+#define freemem				nr_free_pages()
 #define minfree				0
 #define needfree			0	/* # of needed pages */
 #define ptob(pages)			(pages * PAGE_SIZE)