linux_dsm_epyc7002/Documentation/ABI/testing/sysfs-class-pktcdvd
Aishwarya Pant 9b58eae401 Documentation/ABI: clean up sysfs-class-pktcdvd
Clean up the sysfs documentation such that it is in the same format as
described in Documentation/ABI/README. Mainly, the patch moves the
attribute names to the 'What:' field. This might be useful for scripting
and tracking changes in the ABI.

Signed-off-by: Aishwarya Pant <aishpant@gmail.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2018-02-23 08:11:34 -07:00

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sysfs interface
---------------
The pktcdvd module (packet writing driver) creates the following files in the
sysfs: (<devid> is in the format major:minor)
What: /sys/class/pktcdvd/add
What: /sys/class/pktcdvd/remove
What: /sys/class/pktcdvd/device_map
Date: Oct. 2006
KernelVersion: 2.6.20
Contact: Thomas Maier <balagi@justmail.de>
Description:
add: (WO) Write a block device id (major:minor) to
create a new pktcdvd device and map it to the
block device.
remove: (WO) Write the pktcdvd device id (major:minor)
to remove the pktcdvd device.
device_map: (RO) Shows the device mapping in format:
pktcdvd[0-7] <pktdevid> <blkdevid>
What: /sys/class/pktcdvd/pktcdvd[0-7]/dev
What: /sys/class/pktcdvd/pktcdvd[0-7]/uevent
Date: Oct. 2006
KernelVersion: 2.6.20
Contact: Thomas Maier <balagi@justmail.de>
Description:
dev: (RO) Device id
uevent: (WO) To send a uevent
What: /sys/class/pktcdvd/pktcdvd[0-7]/stat/packets_started
What: /sys/class/pktcdvd/pktcdvd[0-7]/stat/packets_finished
What: /sys/class/pktcdvd/pktcdvd[0-7]/stat/kb_written
What: /sys/class/pktcdvd/pktcdvd[0-7]/stat/kb_read
What: /sys/class/pktcdvd/pktcdvd[0-7]/stat/kb_read_gather
What: /sys/class/pktcdvd/pktcdvd[0-7]/stat/reset
Date: Oct. 2006
KernelVersion: 2.6.20
Contact: Thomas Maier <balagi@justmail.de>
Description:
packets_started: (RO) Number of started packets.
packets_finished: (RO) Number of finished packets.
kb_written: (RO) kBytes written.
kb_read: (RO) kBytes read.
kb_read_gather: (RO) kBytes read to fill write packets.
reset: (WO) Write any value to it to reset
pktcdvd device statistic values, like
bytes read/written.
What: /sys/class/pktcdvd/pktcdvd[0-7]/write_queue/size
What: /sys/class/pktcdvd/pktcdvd[0-7]/write_queue/congestion_off
What: /sys/class/pktcdvd/pktcdvd[0-7]/write_queue/congestion_on
Date: Oct. 2006
KernelVersion: 2.6.20
Contact: Thomas Maier <balagi@justmail.de>
Description:
size: (RO) Contains the size of the bio write queue.
congestion_off: (RW) If bio write queue size is below this mark,
accept new bio requests from the block layer.
congestion_on: (RW) If bio write queue size is higher as this
mark, do no longer accept bio write requests
from the block layer and wait till the pktcdvd
device has processed enough bio's so that bio
write queue size is below congestion off mark.
A value of <= 0 disables congestion control.
Example:
--------
To use the pktcdvd sysfs interface directly, you can do:
# create a new pktcdvd device mapped to /dev/hdc
echo "22:0" >/sys/class/pktcdvd/add
cat /sys/class/pktcdvd/device_map
# assuming device pktcdvd0 was created, look at stat's
cat /sys/class/pktcdvd/pktcdvd0/stat/kb_written
# print the device id of the mapped block device
fgrep pktcdvd0 /sys/class/pktcdvd/device_map
# remove device, using pktcdvd0 device id 253:0
echo "253:0" >/sys/class/pktcdvd/remove