Decrease target objects per slab

By decreasing the number of target objects per slab we increase
the likelyhood that a slab can be freed.  This reduces the level
of fragmentation in the slab which has been observed to be a
problem for certain workloads.  The penalty for this is that we
also decrease the speed which need objects can be allocated.

diff --git a/include/sys/kmem.h b/include/sys/kmem.h
index d3972f1ca701c8700dd98e3757d8aeca8e6b1373..72f70c2820ad9fec2c3276ed934ec5f93e16028f 100644 (file)
--- a/include/sys/kmem.h
+++ b/include/sys/kmem.h
@@ -334,7 +334,7 @@ extern struct rw_semaphore spl_kmem_cache_sem;
 
 #define SPL_KMEM_CACHE_DELAY           15      /* Minimum slab release age */
 #define SPL_KMEM_CACHE_REAP            0       /* Default reap everything */
-#define SPL_KMEM_CACHE_OBJ_PER_SLAB    32      /* Target objects per slab */
+#define SPL_KMEM_CACHE_OBJ_PER_SLAB    16      /* Target objects per slab */
 #define SPL_KMEM_CACHE_OBJ_PER_SLAB_MIN        8       /* Minimum objects per slab */
 #define SPL_KMEM_CACHE_ALIGN           8       /* Default object alignment */