Implement per-cpu local caches. This seems to have bough me another

Implement per-cpu local caches.  This seems to have bough me another
factor of 10x improvement on SMP system due to reduced lock contention.
This may put me in the ballpark of what is needed.  We can still further
improve things on NUMA systems by creating an additional L3 cache per
memory node instead of the current global pool.  With luck this won't
be needed.  I should also take another look at the locking now that
everything is working.  There's a good chance I can tighten it up a
little bit and improve things a little more.

   kmem_lock: time (sec)        slabs           objs            hash
   kmem_lock:                   tot/max/calc    tot/max/calc    size/depth
   kmem_lock:  0.000999926      6/6/1           192/192/32      32768/0
   kmem_lock:  0.000999926      4/4/2           128/128/64      32768/0
   kmem_lock:  0.000999926      4/4/4           128/128/128     32768/0
   kmem_lock:  0.000999926      4/4/8           128/128/256     32768/0
   kmem_lock:  0.000999926      4/4/16          128/128/512     32768/0
   kmem_lock:  0.000999926      4/4/32          128/128/1024    32768/0
   kmem_lock:  0.000999926      4/4/64          128/128/2048    32768/0
   kmem_lock:  0.000999926      8/8/128         256/256/4096    32768/0
   kmem_lock:  0.003999704      24/23/256       768/736/8192    32768/1
   kmem_lock:  0.012999038      44/41/512       1408/1312/16384 32768/1
   kmem_lock:  0.051996153      96/93/1024      3072/2976/32768 32768/2
   kmem_lock:  0.181986536      187/184/2048    5984/5888/65536 32768/3
   kmem_lock:  0.655951469      342/339/4096    10944/10848/131072 32768/4

git-svn-id: https://outreach.scidac.gov/svn/spl/trunk@136 7e1ea52c-4ff2-0310-8f11-9dd32ca42a1c