[PATCH v2 4/4] doc: document sysfs queue/cranges attributes
DORMANTno replies
From: Damien Le Moal <hidden>
Date: 2021-07-23 01:22:11
Also in:
linux-ide, linux-scsi
Subsystem:
block layer, documentation, the rest · Maintainers:
Jens Axboe, Jonathan Corbet, Linus Torvalds
Revision v2 of 9 in this series.
Revisions (9)
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 <redacted> --- Documentation/block/queue-sysfs.rst | 30 ++++++++++++++++++++++++++++- 1 file changed, 29 insertions(+), 1 deletion(-)
diff --git a/Documentation/block/queue-sysfs.rst b/Documentation/block/queue-sysfs.rst
index 4dc7f0d499a8..25f4a768f450 100644
--- a/Documentation/block/queue-sysfs.rst
+++ b/Documentation/block/queue-sysfs.rst@@ -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
--
2.31.1