FS-Cache: Fix __fscache_uncache_all_inode_pages()'s outer loop
[linux-2.6.git] / fs / fscache / histogram.c
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  */
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  */
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  */
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  */
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  */
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 };