@@ -4,7 +4,7 @@ Queue sysfs files
This text file will detail the queue files that are located in the sysfs tree
for each block device. Note that stacked devices typically do not export
-any settings, since their queue merely functions are a remapping target.
+any settings, since their queue merely functions as a remapping target.
These files are the ones found in the /sys/block/xxx/queue/ directory.
Files denoted with a RO postfix are readonly and the RW postfix means
@@ -286,4 +286,32 @@ sequential zones of zoned block devices (devices with a zoned attributed
that reports "host-managed" or "host-aware"). This value is always 0 for
regular block devices.
+cranges (RO)
+------------
+
+The presence of this sub-directory of the /sys/block/xxx/queue/ directory
+indicates that the device is capable of executing requests targeting
+different sector ranges in parallel. For instance, single LUN multi-actuator
+hard-disks will likely have a cranges directory if the device correctly
+advertizes the sector ranges of its actuators.
+
+The cranges directory contains one directory per concurrent range, with each
+range described using the sector (RO) attribute file to indicate the first
+sector of the range and the nr_sectors (RO) attribute file to indicate the
+total number of sector in the range starting from the first sector.
+For example, a dual-actuator hard disk will have the following cranges
+entries.::
+
+ $ tree /sys/block/<device>/queue/cranges/
+ /sys/block/<device>/queue/cranges/
+ |-- 0
+ | |-- nr_sectors
+ | `-- sector
+ `-- 1
+ |-- nr_sectors
+ `-- sector
+
+The sector and nr_sectors attributes use 512B sector unit, regardless of
+the actual block size of the device.
+
Jens Axboe <jens.axboe@oracle.com>, February 2009
Update the file Documentation/block/queue-sysfs.rst to add a description of a device queue sysfs entries related to concurrent sector ranges (e.g. concurrent positioning ranges for multi-actuator hard-disks). While at it, also fix a typo in this file introduction paragraph. Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com> --- Documentation/block/queue-sysfs.rst | 30 ++++++++++++++++++++++++++++- 1 file changed, 29 insertions(+), 1 deletion(-)