Documentation/ABI/testing/sysfs-class-pktcdvd

   1 sysfs interface
   2 ---------------
   3 The pktcdvd module (packet writing driver) creates the following files in the
   4 sysfs: (<devid> is in the format major:minor)
   5
   6 What:           /sys/class/pktcdvd/add
   7 What:           /sys/class/pktcdvd/remove
   8 What:           /sys/class/pktcdvd/device_map
   9 Date:           Oct. 2006
  10 KernelVersion:  2.6.20
  11 Contact:        Thomas Maier <balagi@justmail.de>
  12 Description:
  13
  14                 add:            (WO) Write a block device id (major:minor) to
  15                                 create a new pktcdvd device and map it to the
  16                                 block device.
  17
  18                 remove:         (WO) Write the pktcdvd device id (major:minor)
  19                                 to remove the pktcdvd device.
  20
  21                 device_map:     (RO) Shows the device mapping in format:
  22                                 pktcdvd[0-7] <pktdevid> <blkdevid>
  23
  24
  25 What:           /sys/class/pktcdvd/pktcdvd[0-7]/dev
  26 What:           /sys/class/pktcdvd/pktcdvd[0-7]/uevent
  27 Date:           Oct. 2006
  28 KernelVersion:  2.6.20
  29 Contact:        Thomas Maier <balagi@justmail.de>
  30 Description:
  31                 dev:    (RO) Device id
  32
  33                 uevent: (WO) To send a uevent
  34
  35
  36 What:           /sys/class/pktcdvd/pktcdvd[0-7]/stat/packets_started
  37 What:           /sys/class/pktcdvd/pktcdvd[0-7]/stat/packets_finished
  38 What:           /sys/class/pktcdvd/pktcdvd[0-7]/stat/kb_written
  39 What:           /sys/class/pktcdvd/pktcdvd[0-7]/stat/kb_read
  40 What:           /sys/class/pktcdvd/pktcdvd[0-7]/stat/kb_read_gather
  41 What:           /sys/class/pktcdvd/pktcdvd[0-7]/stat/reset
  42 Date:           Oct. 2006
  43 KernelVersion:  2.6.20
  44 Contact:        Thomas Maier <balagi@justmail.de>
  45 Description:
  46                 packets_started:        (RO) Number of started packets.
  47
  48                 packets_finished:       (RO) Number of finished packets.
  49
  50                 kb_written:             (RO) kBytes written.
  51
  52                 kb_read:                (RO) kBytes read.
  53
  54                 kb_read_gather:         (RO) kBytes read to fill write packets.
  55
  56                 reset:                  (WO) Write any value to it to reset
  57                                         pktcdvd device statistic values, like
  58                                         bytes read/written.
  59
  60
  61 What:           /sys/class/pktcdvd/pktcdvd[0-7]/write_queue/size
  62 What:           /sys/class/pktcdvd/pktcdvd[0-7]/write_queue/congestion_off
  63 What:           /sys/class/pktcdvd/pktcdvd[0-7]/write_queue/congestion_on
  64 Date:           Oct. 2006
  65 KernelVersion:  2.6.20
  66 Contact:        Thomas Maier <balagi@justmail.de>
  67 Description:
  68                 size:           (RO) Contains the size of the bio write queue.
  69
  70                 congestion_off: (RW) If bio write queue size is below this mark,
  71                                 accept new bio requests from the block layer.
  72
  73                 congestion_on:  (RW) If bio write queue size is higher as this
  74                                 mark, do no longer accept bio write requests
  75                                 from the block layer and wait till the pktcdvd
  76                                 device has processed enough bio's so that bio
  77                                 write queue size is below congestion off mark.
  78                                 A value of <= 0 disables congestion control.
  79
  80
  81 Example:
  82 --------
  83 To use the pktcdvd sysfs interface directly, you can do:
  84
  85 # create a new pktcdvd device mapped to /dev/hdc
  86 echo "22:0" >/sys/class/pktcdvd/add
  87 cat /sys/class/pktcdvd/device_map
  88 # assuming device pktcdvd0 was created, look at stat's
  89 cat /sys/class/pktcdvd/pktcdvd0/stat/kb_written
  90 # print the device id of the mapped block device
  91 fgrep pktcdvd0 /sys/class/pktcdvd/device_map
  92 # remove device, using pktcdvd0 device id   253:0
  93 echo "253:0" >/sys/class/pktcdvd/remove