1 /* CacheFiles statistics
2 *
3 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
4 * Written by David Howells (dhowells@redhat.com)
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public Licence
8 * as published by the Free Software Foundation; either version
9 * 2 of the Licence, or (at your option) any later version.
10 */
11
12 #include <linux/module.h>
13 #include <linux/proc_fs.h>
14 #include <linux/seq_file.h>
15 #include "internal.h"
16
17 atomic_t cachefiles_lookup_histogram[HZ];
18 atomic_t cachefiles_mkdir_histogram[HZ];
19 atomic_t cachefiles_create_histogram[HZ];
20
21 /*
22 * display the latency histogram
23 */
cachefiles_histogram_show(struct seq_file * m,void * v)24 static int cachefiles_histogram_show(struct seq_file *m, void *v)
25 {
26 unsigned long index;
27 unsigned x, y, z, t;
28
29 switch ((unsigned long) v) {
30 case 1:
31 seq_puts(m, "JIFS SECS LOOKUPS MKDIRS CREATES\n");
32 return 0;
33 case 2:
34 seq_puts(m, "===== ===== ========= ========= =========\n");
35 return 0;
36 default:
37 index = (unsigned long) v - 3;
38 x = atomic_read(&cachefiles_lookup_histogram[index]);
39 y = atomic_read(&cachefiles_mkdir_histogram[index]);
40 z = atomic_read(&cachefiles_create_histogram[index]);
41 if (x == 0 && y == 0 && z == 0)
42 return 0;
43
44 t = (index * 1000) / HZ;
45
46 seq_printf(m, "%4lu 0.%03u %9u %9u %9u\n", index, t, x, y, z);
47 return 0;
48 }
49 }
50
51 /*
52 * set up the iterator to start reading from the first line
53 */
cachefiles_histogram_start(struct seq_file * m,loff_t * _pos)54 static void *cachefiles_histogram_start(struct seq_file *m, loff_t *_pos)
55 {
56 if ((unsigned long long)*_pos >= HZ + 2)
57 return NULL;
58 if (*_pos == 0)
59 *_pos = 1;
60 return (void *)(unsigned long) *_pos;
61 }
62
63 /*
64 * move to the next line
65 */
cachefiles_histogram_next(struct seq_file * m,void * v,loff_t * pos)66 static void *cachefiles_histogram_next(struct seq_file *m, void *v, loff_t *pos)
67 {
68 (*pos)++;
69 return (unsigned long long)*pos > HZ + 2 ?
70 NULL : (void *)(unsigned long) *pos;
71 }
72
73 /*
74 * clean up after reading
75 */
cachefiles_histogram_stop(struct seq_file * m,void * v)76 static void cachefiles_histogram_stop(struct seq_file *m, void *v)
77 {
78 }
79
80 static const struct seq_operations cachefiles_histogram_ops = {
81 .start = cachefiles_histogram_start,
82 .stop = cachefiles_histogram_stop,
83 .next = cachefiles_histogram_next,
84 .show = cachefiles_histogram_show,
85 };
86
87 /*
88 * initialise the /proc/fs/cachefiles/ directory
89 */
cachefiles_proc_init(void)90 int __init cachefiles_proc_init(void)
91 {
92 _enter("");
93
94 if (!proc_mkdir("fs/cachefiles", NULL))
95 goto error_dir;
96
97 if (!proc_create_seq("fs/cachefiles/histogram", S_IFREG | 0444, NULL,
98 &cachefiles_histogram_ops))
99 goto error_histogram;
100
101 _leave(" = 0");
102 return 0;
103
104 error_histogram:
105 remove_proc_entry("fs/cachefiles", NULL);
106 error_dir:
107 _leave(" = -ENOMEM");
108 return -ENOMEM;
109 }
110
111 /*
112 * clean up the /proc/fs/cachefiles/ directory
113 */
cachefiles_proc_cleanup(void)114 void cachefiles_proc_cleanup(void)
115 {
116 remove_proc_entry("fs/cachefiles/histogram", NULL);
117 remove_proc_entry("fs/cachefiles", NULL);
118 }
119