Change spl_kmem_cache_expire default setting to 2

This behavior is more consistent with the way memory reclaim
is expected to work under Linux.

Signed-off-by: Richard Yao <ryao@gentoo.org>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #349

diff --git a/module/spl/spl-kmem.c b/module/spl/spl-kmem.c
index e43e9170b44d2e22c4c0dc320c149ccc5455cbc7..55c467b97b62f174493187c993e7ea69abdcb717 100644 (file)
--- a/module/spl/spl-kmem.c
+++ b/module/spl/spl-kmem.c
@@ -38,10 +38,11 @@
  * kmem_cache behavior.  The idea is that per-cpu objects which haven't been
  * accessed in several seconds should be returned to the cache.  On the other
  * hand Linux slabs never move objects back to the slabs unless there is
- * memory pressure on the system.  By default both methods are disabled, but
- * may be enabled by setting KMC_EXPIRE_AGE or KMC_EXPIRE_MEM.
+ * memory pressure on the system.  By default the Linux method is enabled
+ * because it has been shown to improve responsiveness on low memory systems.
+ * This policy may be changed by setting KMC_EXPIRE_AGE or KMC_EXPIRE_MEM.
  */
-unsigned int spl_kmem_cache_expire = 0;
+unsigned int spl_kmem_cache_expire = KMC_EXPIRE_MEM;
 EXPORT_SYMBOL(spl_kmem_cache_expire);
 module_param(spl_kmem_cache_expire, uint, 0644);
 MODULE_PARM_DESC(spl_kmem_cache_expire, "By age (0x1) or low memory (0x2)");