Root/
1 | dm-queue-length |
2 | =============== |
3 | |
4 | dm-queue-length is a path selector module for device-mapper targets, |
5 | which selects a path with the least number of in-flight I/Os. |
6 | The path selector name is 'queue-length'. |
7 | |
8 | Table parameters for each path: [<repeat_count>] |
9 | <repeat_count>: The number of I/Os to dispatch using the selected |
10 | path before switching to the next path. |
11 | If not given, internal default is used. To check |
12 | the default value, see the activated table. |
13 | |
14 | Status for each path: <status> <fail-count> <in-flight> |
15 | <status>: 'A' if the path is active, 'F' if the path is failed. |
16 | <fail-count>: The number of path failures. |
17 | <in-flight>: The number of in-flight I/Os on the path. |
18 | |
19 | |
20 | Algorithm |
21 | ========= |
22 | |
23 | dm-queue-length increments/decrements 'in-flight' when an I/O is |
24 | dispatched/completed respectively. |
25 | dm-queue-length selects a path with the minimum 'in-flight'. |
26 | |
27 | |
28 | Examples |
29 | ======== |
30 | In case that 2 paths (sda and sdb) are used with repeat_count == 128. |
31 | |
32 | # echo "0 10 multipath 0 0 1 1 queue-length 0 2 1 8:0 128 8:16 128" \ |
33 | dmsetup create test |
34 | # |
35 | # dmsetup table |
36 | test: 0 10 multipath 0 0 1 1 queue-length 0 2 1 8:0 128 8:16 128 |
37 | # |
38 | # dmsetup status |
39 | test: 0 10 multipath 2 0 0 0 1 1 E 0 2 1 8:0 A 0 0 8:16 A 0 0 |
40 |
Branches:
ben-wpan
ben-wpan-stefan
javiroman/ks7010
jz-2.6.34
jz-2.6.34-rc5
jz-2.6.34-rc6
jz-2.6.34-rc7
jz-2.6.35
jz-2.6.36
jz-2.6.37
jz-2.6.38
jz-2.6.39
jz-3.0
jz-3.1
jz-3.11
jz-3.12
jz-3.13
jz-3.15
jz-3.16
jz-3.18-dt
jz-3.2
jz-3.3
jz-3.4
jz-3.5
jz-3.6
jz-3.6-rc2-pwm
jz-3.9
jz-3.9-clk
jz-3.9-rc8
jz47xx
jz47xx-2.6.38
master
Tags:
od-2011-09-04
od-2011-09-18
v2.6.34-rc5
v2.6.34-rc6
v2.6.34-rc7
v3.9