[PATCH v4 4/5] doc: document sysfs queue/cranges attributes
From: Damien Le Moal <hidden>
Date: 2021-08-12 02:26:56
Also in:
linux-block
Subsystem:
block layer, documentation, the rest · Maintainers:
Jens Axboe, Jonathan Corbet, Linus Torvalds
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> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Christoph Hellwig <hch@lst.de> --- Documentation/block/queue-sysfs.rst | 28 ++++++++++++++++++++++++++++ 1 file changed, 28 insertions(+)
diff --git a/Documentation/block/queue-sysfs.rst b/Documentation/block/queue-sysfs.rst
index 4dc7f0d499a8..757609bbb1e2 100644
--- a/Documentation/block/queue-sysfs.rst
+++ b/Documentation/block/queue-sysfs.rst@@ -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
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2.31.1