Illumos #175: zfs vdev cache consumes excessive memory

[zfs.git] / module / zfs / vdev_cache.c

diff --git a/module/zfs/vdev_cache.c b/module/zfs/vdev_cache.c
index 0d1fe7d..e2f8040 100644 (file)
--- a/module/zfs/vdev_cache.c
+++ b/module/zfs/vdev_cache.c
@@ -71,9 +71,16 @@
  * 1<<zfs_vdev_cache_bshift byte reads by the vdev_cache (aka software
  * track buffer).  At most zfs_vdev_cache_size bytes will be kept in each
  * vdev's vdev_cache.
+ *
+ * TODO: Note that with the current ZFS code, it turns out that the
+ * vdev cache is not helpful, and in some cases actually harmful.  It
+ * is better if we disable this.  Once some time has passed, we should
+ * actually remove this to simplify the code.  For now we just disable
+ * it by setting the zfs_vdev_cache_size to zero.  Note that Solaris 11
+ * has made these same changes.
  */
 int zfs_vdev_cache_max = 1<<14;                        /* 16KB */
-int zfs_vdev_cache_size = 10ULL << 20;         /* 10MB */
+int zfs_vdev_cache_size = 0;
 int zfs_vdev_cache_bshift = 16;
 
 #define        VCBS (1 << zfs_vdev_cache_bshift)       /* 64KB */