archive mirror
 help / color / mirror / Atom feed
From: Damien Le Moal <>
To:, Jens Axboe <>,,
	"Martin K . Petersen" <>,
Cc: Hannes Reinecke <>
Subject: [PATCH v2 4/4] doc: document sysfs queue/cranges attributes
Date: Fri, 23 Jul 2021 10:22:00 +0900	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

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 <>
 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
+        $ 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 <>, February 2009

      parent reply	other threads:[~2021-07-23  1:22 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-23  1:21 [PATCH v2 0/4] Initial support for multi-actuator HDDs Damien Le Moal
2021-07-23  1:21 ` [PATCH v2 1/4] block: Add concurrent positioning ranges support Damien Le Moal
2021-07-23  1:21 ` [PATCH v2 2/4] scsi: sd: add " Damien Le Moal
2021-07-23  1:21 ` [PATCH v2 3/4] libata: support concurrent positioning ranges log Damien Le Moal
2021-07-23  1:22 ` Damien Le Moal [this message]

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \ \ \ \ \ \ \ \ \

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).