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-rw-r--r--Documentation/block/queue-sysfs.txt64
1 files changed, 43 insertions, 21 deletions
diff --git a/Documentation/block/queue-sysfs.txt b/Documentation/block/queue-sysfs.txt
index 83b457e24bba..b40b5b7cebd9 100644
--- a/Documentation/block/queue-sysfs.txt
+++ b/Documentation/block/queue-sysfs.txt
@@ -14,6 +14,15 @@ add_random (RW)
This file allows to turn off the disk entropy contribution. Default
value of this file is '1'(on).
+chunk_sectors (RO)
+------------------
+This has different meaning depending on the type of the block device.
+For a RAID device (dm-raid), chunk_sectors indicates the size in 512B sectors
+of the RAID volume stripe segment. For a zoned block device, either host-aware
+or host-managed, chunk_sectors indicates the size in 512B sectors of the zones
+of the device, with the eventual exception of the last zone of the device which
+may be smaller.
+
dax (RO)
--------
This file indicates whether the device supports Direct Access (DAX),
@@ -43,6 +52,16 @@ large discards are issued, setting this value lower will make Linux issue
smaller discards and potentially help reduce latencies induced by large
discard operations.
+discard_zeroes_data (RO)
+------------------------
+Obsolete. Always zero.
+
+fua (RO)
+--------
+Whether or not the block driver supports the FUA flag for write requests.
+FUA stands for Force Unit Access. If the FUA flag is set that means that
+write requests must bypass the volatile cache of the storage device.
+
hw_sector_size (RO)
-------------------
This is the hardware sector size of the device, in bytes.
@@ -83,14 +102,19 @@ logical_block_size (RO)
-----------------------
This is the logical block size of the device, in bytes.
+max_discard_segments (RO)
+-------------------------
+The maximum number of DMA scatter/gather entries in a discard request.
+
max_hw_sectors_kb (RO)
----------------------
This is the maximum number of kilobytes supported in a single data transfer.
max_integrity_segments (RO)
---------------------------
-When read, this file shows the max limit of integrity segments as
-set by block layer which a hardware controller can handle.
+Maximum number of elements in a DMA scatter/gather list with integrity
+data that will be submitted by the block layer core to the associated
+block driver.
max_sectors_kb (RW)
-------------------
@@ -100,11 +124,12 @@ size allowed by the hardware.
max_segments (RO)
-----------------
-Maximum number of segments of the device.
+Maximum number of elements in a DMA scatter/gather list that is submitted
+to the associated block driver.
max_segment_size (RO)
---------------------
-Maximum segment size of the device.
+Maximum size in bytes of a single element in a DMA scatter/gather list.
minimum_io_size (RO)
--------------------
@@ -132,6 +157,12 @@ per-block-cgroup request pool. IOW, if there are N block cgroups,
each request queue may have up to N request pools, each independently
regulated by nr_requests.
+nr_zones (RO)
+-------------
+For zoned block devices (zoned attribute indicating "host-managed" or
+"host-aware"), this indicates the total number of zones of the device.
+This is always 0 for regular block devices.
+
optimal_io_size (RO)
--------------------
This is the optimal IO size reported by the device.
@@ -185,8 +216,8 @@ This is the number of bytes the device can write in a single write-same
command. A value of '0' means write-same is not supported by this
device.
-wb_lat_usec (RW)
-----------------
+wbt_lat_usec (RW)
+-----------------
If the device is registered for writeback throttling, then this file shows
the target minimum read latency. If this latency is exceeded in a given
window of time (see wb_window_usec), then the writeback throttling will start
@@ -201,6 +232,12 @@ blk-throttle makes decision based on the samplings. Lower time means cgroups
have more smooth throughput, but higher CPU overhead. This exists only when
CONFIG_BLK_DEV_THROTTLING_LOW is enabled.
+write_zeroes_max_bytes (RO)
+---------------------------
+For block drivers that support REQ_OP_WRITE_ZEROES, the maximum number of
+bytes that can be zeroed at once. The value 0 means that REQ_OP_WRITE_ZEROES
+is not supported.
+
zoned (RO)
----------
This indicates if the device is a zoned block device and the zone model of the
@@ -213,19 +250,4 @@ devices are described in the ZBC (Zoned Block Commands) and ZAC
do not support zone commands, they will be treated as regular block devices
and zoned will report "none".
-nr_zones (RO)
--------------
-For zoned block devices (zoned attribute indicating "host-managed" or
-"host-aware"), this indicates the total number of zones of the device.
-This is always 0 for regular block devices.
-
-chunk_sectors (RO)
-------------------
-This has different meaning depending on the type of the block device.
-For a RAID device (dm-raid), chunk_sectors indicates the size in 512B sectors
-of the RAID volume stripe segment. For a zoned block device, either host-aware
-or host-managed, chunk_sectors indicates the size in 512B sectors of the zones
-of the device, with the eventual exception of the last zone of the device which
-may be smaller.
-
Jens Axboe <jens.axboe@oracle.com>, February 2009