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From: Damien Le Moal <damien.lemoal@wdc.com>
To: Jens Axboe <axboe@kernel.dk>,
	linux-block@vger.kernel.org,
	"Martin K . Petersen" <martin.petersen@oracle.com>,
	linux-scsi@vger.kernel.org
Subject: [PATCH v6 4/5] doc: document sysfs queue/independent_access_ranges attributes
Date: Fri, 27 Aug 2021 16:50:43 +0900	[thread overview]
Message-ID: <20210827075045.642269-5-damien.lemoal@wdc.com> (raw)
In-Reply-To: <20210827075045.642269-1-damien.lemoal@wdc.com>

Update the file Documentation/block/queue-sysfs.rst to add a description
of a device queue sysfs entries related to independent access ranges
(e.g. concurrent positioning ranges for multi-actuator hard-disks).

Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
---
 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..17eef55434e7 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.
 
+independent_access_ranges (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 an independent_access_ranges directory if the
+device correctly advertizes the sector ranges of its actuators.
+
+The independent_access_ranges directory contains one directory per access
+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 of the range.  For example, a dual-actuator hard disk will have the
+following independent_access_ranges entries.::
+
+        $ tree /sys/block/<device>/queue/independent_access_ranges/
+        /sys/block/<device>/queue/independent_access_ranges/
+        |-- 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


  parent reply	other threads:[~2021-08-27  7:50 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-27  7:50 [PATCH v6 0/5] Initial support for multi-actuator HDDs Damien Le Moal
2021-08-27  7:50 ` [PATCH v6 1/5] block: Add independent access ranges support Damien Le Moal
2021-08-27  7:50 ` [PATCH v6 2/5] scsi: sd: add concurrent positioning " Damien Le Moal
2021-08-27  7:50 ` [PATCH v6 3/5] libata: support concurrent positioning ranges log Damien Le Moal
2021-08-27  7:50 ` Damien Le Moal [this message]
2021-08-27  7:50 ` [PATCH v6 5/5] doc: Fix typo in request queue sysfs documentation Damien Le Moal
2021-08-27 13:58 ` [PATCH v6 0/5] Initial support for multi-actuator HDDs Phillip Susi
2021-08-27 14:28   ` Tim Walker
2021-08-27 16:41     ` Christoph Hellwig
2021-08-27 17:00       ` Tim Walker
2021-08-29 22:55       ` Damien Le Moal
2021-08-27 17:34     ` Phillip Susi
2021-08-29 22:50       ` Damien Le Moal

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