0001 sysfs interface
0002 ---------------
0003 The pktcdvd module (packet writing driver) creates the following files in the
0004 sysfs: (<devid> is in the format major:minor)
0005
0006 What: /sys/class/pktcdvd/add
0007 What: /sys/class/pktcdvd/remove
0008 What: /sys/class/pktcdvd/device_map
0009 Date: Oct. 2006
0010 KernelVersion: 2.6.20
0011 Contact: Thomas Maier <balagi@justmail.de>
0012 Description:
0013
0014 ========== ==============================================
0015 add (WO) Write a block device id (major:minor) to
0016 create a new pktcdvd device and map it to the
0017 block device.
0018
0019 remove (WO) Write the pktcdvd device id (major:minor)
0020 to remove the pktcdvd device.
0021
0022 device_map (RO) Shows the device mapping in format:
0023 pktcdvd[0-7] <pktdevid> <blkdevid>
0024 ========== ==============================================
0025
0026
0027 What: /sys/class/pktcdvd/pktcdvd[0-7]/dev
0028 What: /sys/class/pktcdvd/pktcdvd[0-7]/uevent
0029 Date: Oct. 2006
0030 KernelVersion: 2.6.20
0031 Contact: Thomas Maier <balagi@justmail.de>
0032 Description:
0033 dev: (RO) Device id
0034
0035 uevent: (WO) To send a uevent
0036
0037
0038 What: /sys/class/pktcdvd/pktcdvd[0-7]/stat/packets_started
0039 What: /sys/class/pktcdvd/pktcdvd[0-7]/stat/packets_finished
0040 What: /sys/class/pktcdvd/pktcdvd[0-7]/stat/kb_written
0041 What: /sys/class/pktcdvd/pktcdvd[0-7]/stat/kb_read
0042 What: /sys/class/pktcdvd/pktcdvd[0-7]/stat/kb_read_gather
0043 What: /sys/class/pktcdvd/pktcdvd[0-7]/stat/reset
0044 Date: Oct. 2006
0045 KernelVersion: 2.6.20
0046 Contact: Thomas Maier <balagi@justmail.de>
0047 Description:
0048 packets_started: (RO) Number of started packets.
0049
0050 packets_finished: (RO) Number of finished packets.
0051
0052 kb_written: (RO) kBytes written.
0053
0054 kb_read: (RO) kBytes read.
0055
0056 kb_read_gather: (RO) kBytes read to fill write packets.
0057
0058 reset: (WO) Write any value to it to reset
0059 pktcdvd device statistic values, like
0060 bytes read/written.
0061
0062
0063 What: /sys/class/pktcdvd/pktcdvd[0-7]/write_queue/size
0064 What: /sys/class/pktcdvd/pktcdvd[0-7]/write_queue/congestion_off
0065 What: /sys/class/pktcdvd/pktcdvd[0-7]/write_queue/congestion_on
0066 Date: Oct. 2006
0067 KernelVersion: 2.6.20
0068 Contact: Thomas Maier <balagi@justmail.de>
0069 Description:
0070 ============== ================================================
0071 size (RO) Contains the size of the bio write queue.
0072
0073 congestion_off (RW) If bio write queue size is below this mark,
0074 accept new bio requests from the block layer.
0075
0076 congestion_on (RW) If bio write queue size is higher as this
0077 mark, do no longer accept bio write requests
0078 from the block layer and wait till the pktcdvd
0079 device has processed enough bio's so that bio
0080 write queue size is below congestion off mark.
0081 A value of <= 0 disables congestion control.
0082 ============== ================================================
0083
0084
0085 Example:
0086 --------
0087 To use the pktcdvd sysfs interface directly, you can do::
0088
0089 # create a new pktcdvd device mapped to /dev/hdc
0090 echo "22:0" >/sys/class/pktcdvd/add
0091 cat /sys/class/pktcdvd/device_map
0092 # assuming device pktcdvd0 was created, look at stat's
0093 cat /sys/class/pktcdvd/pktcdvd0/stat/kb_written
0094 # print the device id of the mapped block device
0095 fgrep pktcdvd0 /sys/class/pktcdvd/device_map
0096 # remove device, using pktcdvd0 device id 253:0
0097 echo "253:0" >/sys/class/pktcdvd/remove
