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Commit f9824952 authored by Damien Le Moal's avatar Damien Le Moal Committed by Jens Axboe
Browse files

block: update sysfs documentation 



Add the description of the zoned, nr_zones and chunk_sectors sysfs queue
attributes to Documentation/block/queue-sysfs.txt. The description of
the zoned and chunk_sector attributes are mostly copied from
ABI/testing/sysfs-block (added a typo fix). While at it, also fix a
typo in the description of the io_poll_delay attribute.

nr_zones description is also added to ABI/testing/sysfs-block and
contact email address updated for the zoned attribute.

Signed-off-by: default avatarDamien Le Moal <damien.lemoal@wdc.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 38a3499f

Documentation/ABI/testing/sysfs-block

+10 −2
Original line number Diff line number Diff line
@@ -244,7 +244,7 @@ Description: 


What:		/sys/block/<disk>/queue/zoned

Date:		September 2016

Contact:	Damien Le Moal <damien.lemoal@hgst.com>

Contact:	Damien Le Moal <damien.lemoal@wdc.com>

Description:

		zoned indicates if the device is a zoned block device

		and the zone model of the device if it is indeed zoned.
@@ -259,6 +259,14 @@ Description: 
		zone commands, they will be treated as regular block

		devices and zoned will report "none".



What:		/sys/block/<disk>/queue/nr_zones

Date:		November 2018

Contact:	Damien Le Moal <damien.lemoal@wdc.com>

Description:

		nr_zones indicates the total number of zones of a zoned block

		device ("host-aware" or "host-managed" zone model). For regular

		block devices, the value is always 0.



What:		/sys/block/<disk>/queue/chunk_sectors

Date:		September 2016

Contact:	Hannes Reinecke <hare@suse.com>
@@ -268,6 +276,6 @@ Description: 
		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 of 512B sectors of the zones of the device, with

		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.

Documentation/block/queue-sysfs.txt

+28 −1
Original line number Diff line number Diff line
@@ -64,7 +64,7 @@ guess, the kernel will put the process issuing IO to sleep for an amount 
of time, before entering a classic poll loop. This mode might be a

little slower than pure classic polling, but it will be more efficient.

If set to a value larger than 0, the kernel will put the process issuing

IO to sleep for this amont of microseconds before entering classic

IO to sleep for this amount of microseconds before entering classic

polling.



iostats (RW)
@@ -194,4 +194,31 @@ 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.



zoned (RO)

----------

This indicates if the device is a zoned block device and the zone model of the

device if it is indeed zoned. The possible values indicated by zoned are

"none" for regular block devices and "host-aware" or "host-managed" for zoned

block devices. The characteristics of host-aware and host-managed zoned block

devices are described in the ZBC (Zoned Block Commands) and ZAC

(Zoned Device ATA Command Set) standards. These standards also define the

"drive-managed" zone model. However, since drive-managed zoned block devices

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