blk-cgroup: Lower minimum weight from 100 to 10.

We've found that we still get good, useful isolation at weights this
low. I'd like to adjust the minimum so that any other changes can take
these values into account.

Signed-off-by: Justin TerAvest <teravest@google.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>

Documentation/cgroups/blkio-controller.txt

@@ -140,7 +140,7 @@ Proportional weight policy files
 	- Specifies per cgroup weight. This is default weight of the group
 	  on all the devices until and unless overridden by per device rule.
 	  (See blkio.weight_device).
-	  Currently allowed range of weights is from 100 to 1000.
+	  Currently allowed range of weights is from 10 to 1000.
 
 - blkio.weight_device
 	- One can specify per cgroup per device rules using this interface.

block/blk-cgroup.h

@@ -240,7 +240,7 @@ static inline char *blkg_path(struct blkio_group *blkg) { return NULL; }
 
 #endif
 
-#define BLKIO_WEIGHT_MIN	100
+#define BLKIO_WEIGHT_MIN	10
 #define BLKIO_WEIGHT_MAX	1000
 #define BLKIO_WEIGHT_DEFAULT	500