xref: /netbsd-src/external/cddl/dtracetoolkit/dist/Docs/Examples/vopstat_example.txt (revision c29d51755812ace2e87aeefdb06cb2b4dac7087a)
1The following are demonstrations of the vopstat script.
2
3
4By default, vopstat traces activity at the vnode interface and prints
5summaries every five seconds. It will either trace all filesystems or
6just the mountpoint specified.
7
8Here it was run on /extra1, while a tar command archived /extra1,
9
10   # ./vopstat /extra1
11   VOP Physical IO                                                   Count
12   fop_getpage                                                          66
13
14   VOP Count                                                         Count
15   fop_readdir                                                           1
16   fop_read                                                              2
17   fop_cmp                                                               2
18   fop_seek                                                              3
19   fop_close                                                             7
20   fop_open                                                             10
21   fop_getattr                                                          12
22   fop_access                                                           13
23   fop_lookup                                                           16
24   fop_rwunlock                                                       3802
25   fop_rwlock                                                         3802
26   fop_putpage                                                        4701
27   fop_getpage                                                        6648
28   fop_dispose                                                       19109
29
30   VOP Wall Time                                                  mSeconds
31   fop_readdir                                                           0
32   fop_cmp                                                               0
33   fop_read                                                              0
34   fop_seek                                                              0
35   fop_close                                                             0
36   fop_open                                                              0
37   fop_access                                                            0
38   fop_getattr                                                           0
39   fop_lookup                                                            0
40   fop_rwunlock                                                         64
41   fop_putpage                                                          86
42   fop_rwlock                                                           93
43   fop_dispose                                                         346
44   fop_getpage                                                         402
45   ^C
46
47There were 66 calls for physical I/O operations, fop_getpage, as files
48were read from disk. The VOP Count show that there were many calls to
49fop_putpage and fop_getpage, as tar works its way through files; and
50many more to fop_dispose. The total elaspsed time for these calls
51are listed at the bottom, in milleseconds.
52
53This rate of events will put some pressure on the DTrace buffer,
54you may see dynamic variable drops.
55
56
57
58vopstat also has a -t option to trace activity. Here it is run on /extra1
59while an "ls" command listed files from that directory,
60
61# ./vopstat -t /extra1
62   Event           Device                                                    Path RW     Size   Offset
63-> fop_getattr     -                                                      /extra1  -        0        0
64<- fop_getattr     -                                                      /extra1  -        0        0
65-> fop_access      -                                                      /extra1  -        0        0
66<- fop_access      -                                                      /extra1  -        0        0
67-> fop_open        -                                                      /extra1  -        0        0
68<- fop_open        -                                                      /extra1  -        0        0
69-> fop_getattr     -                                                      /extra1  -        0        0
70<- fop_getattr     -                                                      /extra1  -        0        0
71-> fop_rwlock      -                                                      /extra1  -        0        0
72<- fop_rwlock      -                                                      /extra1  -        0        0
73-> fop_readdir     -                                                      /extra1  -        0        0
74-> fop_getpage     -                                                      /extra1  -        0        0
75<- fop_getpage     -                                                      /extra1  -        0        0
76-> fop_rwunlock    -                                                      /extra1  -        0        0
77<- fop_rwunlock    -                                                      /extra1  -        0        0
78-> fop_rwlock      -                                                      /extra1  -        0        0
79<- fop_rwlock      -                                                      /extra1  -        0        0
80-> fop_readdir     -                                                      /extra1  -        0        0
81<- fop_readdir     -                                                      /extra1  -        0        0
82-> fop_rwunlock    -                                                      /extra1  -        0        0
83<- fop_rwunlock    -                                                      /extra1  -        0        0
84-> fop_close       -                                                      /extra1  -        0      512
85<- fop_close       -                                                      /extra1  -        0      512
86^C
87
88Each call can be seen as it happened, including the entry and return of
89these calls.
90