1 /* FS-Cache latency histogram
2 *
3 * Copyright (C) 2008 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 #define FSCACHE_DEBUG_LEVEL THREAD
13 #include <linux/module.h>
14 #include <linux/proc_fs.h>
15 #include <linux/seq_file.h>
16 #include "internal.h"
17
18 atomic_t fscache_obj_instantiate_histogram[HZ];
19 atomic_t fscache_objs_histogram[HZ];
20 atomic_t fscache_ops_histogram[HZ];
21 atomic_t fscache_retrieval_delay_histogram[HZ];
22 atomic_t fscache_retrieval_histogram[HZ];
23
24 /*
25 * display the time-taken histogram
26 */
fscache_histogram_show(struct seq_file * m,void * v)27 static int fscache_histogram_show(struct seq_file *m, void *v)
28 {
29 unsigned long index;
30 unsigned n[5], t;
31
32 switch ((unsigned long) v) {
33 case 1:
34 seq_puts(m, "JIFS SECS OBJ INST OP RUNS OBJ RUNS "
35 " RETRV DLY RETRIEVLS\n");
36 return 0;
37 case 2:
38 seq_puts(m, "===== ===== ========= ========= ========="
39 " ========= =========\n");
40 return 0;
41 default:
42 index = (unsigned long) v - 3;
43 n[0] = atomic_read(&fscache_obj_instantiate_histogram[index]);
44 n[1] = atomic_read(&fscache_ops_histogram[index]);
45 n[2] = atomic_read(&fscache_objs_histogram[index]);
46 n[3] = atomic_read(&fscache_retrieval_delay_histogram[index]);
47 n[4] = atomic_read(&fscache_retrieval_histogram[index]);
48 if (!(n[0] | n[1] | n[2] | n[3] | n[4]))
49 return 0;
50
51 t = (index * 1000) / HZ;
52
53 seq_printf(m, "%4lu 0.%03u %9u %9u %9u %9u %9u\n",
54 index, t, n[0], n[1], n[2], n[3], n[4]);
55 return 0;
56 }
57 }
58
59 /*
60 * set up the iterator to start reading from the first line
61 */
fscache_histogram_start(struct seq_file * m,loff_t * _pos)62 static void *fscache_histogram_start(struct seq_file *m, loff_t *_pos)
63 {
64 if ((unsigned long long)*_pos >= HZ + 2)
65 return NULL;
66 if (*_pos == 0)
67 *_pos = 1;
68 return (void *)(unsigned long) *_pos;
69 }
70
71 /*
72 * move to the next line
73 */
fscache_histogram_next(struct seq_file * m,void * v,loff_t * pos)74 static void *fscache_histogram_next(struct seq_file *m, void *v, loff_t *pos)
75 {
76 (*pos)++;
77 return (unsigned long long)*pos > HZ + 2 ?
78 NULL : (void *)(unsigned long) *pos;
79 }
80
81 /*
82 * clean up after reading
83 */
fscache_histogram_stop(struct seq_file * m,void * v)84 static void fscache_histogram_stop(struct seq_file *m, void *v)
85 {
86 }
87
88 static const struct seq_operations fscache_histogram_ops = {
89 .start = fscache_histogram_start,
90 .stop = fscache_histogram_stop,
91 .next = fscache_histogram_next,
92 .show = fscache_histogram_show,
93 };
94
95 /*
96 * open "/proc/fs/fscache/histogram" to provide latency data
97 */
fscache_histogram_open(struct inode * inode,struct file * file)98 static int fscache_histogram_open(struct inode *inode, struct file *file)
99 {
100 return seq_open(file, &fscache_histogram_ops);
101 }
102
103 const struct file_operations fscache_histogram_fops = {
104 .owner = THIS_MODULE,
105 .open = fscache_histogram_open,
106 .read = seq_read,
107 .llseek = seq_lseek,
108 .release = seq_release,
109 };
110