Documentation/ABI/testing/sysfs-class-pktcdvd

   1 What:           /sys/class/pktcdvd/
   2 Date:           Oct. 2006
   3 KernelVersion:  2.6.20
   4 Contact:        Thomas Maier <balagi@justmail.de>
   5 Description:
   6
   7 sysfs interface
   8 ---------------
   9
  10 The pktcdvd module (packet writing driver) creates
  11 these files in the sysfs:
  12 (<devid> is in format  major:minor )
  13
  14 /sys/class/pktcdvd/
  15     add            (0200)  Write a block device id (major:minor)
  16                            to create a new pktcdvd device and map
  17                            it to the block device.
  18
  19     remove         (0200)  Write the pktcdvd device id (major:minor)
  20                            to it to remove the pktcdvd device.
  21
  22     device_map     (0444)  Shows the device mapping in format:
  23                              pktcdvd[0-7] <pktdevid> <blkdevid>
  24
  25 /sys/class/pktcdvd/pktcdvd[0-7]/
  26     dev                   (0444) Device id
  27     uevent                (0200) To send an uevent.
  28
  29 /sys/class/pktcdvd/pktcdvd[0-7]/stat/
  30     packets_started       (0444) Number of started packets.
  31     packets_finished      (0444) Number of finished packets.
  32
  33     kb_written            (0444) kBytes written.
  34     kb_read               (0444) kBytes read.
  35     kb_read_gather        (0444) kBytes read to fill write packets.
  36
  37     reset                 (0200) Write any value to it to reset
  38                                  pktcdvd device statistic values, like
  39                                  bytes read/written.
  40
  41 /sys/class/pktcdvd/pktcdvd[0-7]/write_queue/
  42     size                  (0444) Contains the size of the bio write
  43                                  queue.
  44
  45     congestion_off        (0644) If bio write queue size is below
  46                                  this mark, accept new bio requests
  47                                  from the block layer.
  48
  49     congestion_on         (0644) If bio write queue size is higher
  50                                  as this mark, do no longer accept
  51                                  bio write requests from the block
  52                                  layer and wait till the pktcdvd
  53                                  device has processed enough bio's
  54                                  so that bio write queue size is
  55                                  below congestion off mark.
  56                                  A value of <= 0 disables congestion
  57                                  control.
  58
  59
  60 Example:
  61 --------
  62 To use the pktcdvd sysfs interface directly, you can do:
  63
  64 # create a new pktcdvd device mapped to /dev/hdc
  65 echo "22:0" >/sys/class/pktcdvd/add
  66 cat /sys/class/pktcdvd/device_map
  67 # assuming device pktcdvd0 was created, look at stat's
  68 cat /sys/class/pktcdvd/pktcdvd0/stat/kb_written
  69 # print the device id of the mapped block device
  70 fgrep pktcdvd0 /sys/class/pktcdvd/device_map
  71 # remove device, using pktcdvd0 device id   253:0
  72 echo "253:0" >/sys/class/pktcdvd/remove