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[linux-2.6] / 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