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 RETRV DLY RETRIEVLS\n");
35 return 0;
36 case 2:
37 seq_puts(m, "===== ===== ========= ========= ========= ========= =========\n");
38 return 0;
39 default:
40 index = (unsigned long) v - 3;
41 n[0] = atomic_read(&fscache_obj_instantiate_histogram[index]);
42 n[1] = atomic_read(&fscache_ops_histogram[index]);
43 n[2] = atomic_read(&fscache_objs_histogram[index]);
44 n[3] = atomic_read(&fscache_retrieval_delay_histogram[index]);
45 n[4] = atomic_read(&fscache_retrieval_histogram[index]);
46 if (!(n[0] | n[1] | n[2] | n[3] | n[4]))
47 return 0;
48
49 t = (index * 1000) / HZ;
50
51 seq_printf(m, "%4lu 0.%03u %9u %9u %9u %9u %9u\n",
52 index, t, n[0], n[1], n[2], n[3], n[4]);
53 return 0;
54 }
55 }
56
57 /*
58 * set up the iterator to start reading from the first line
59 */
fscache_histogram_start(struct seq_file * m,loff_t * _pos)60 static void *fscache_histogram_start(struct seq_file *m, loff_t *_pos)
61 {
62 if ((unsigned long long)*_pos >= HZ + 2)
63 return NULL;
64 if (*_pos == 0)
65 *_pos = 1;
66 return (void *)(unsigned long) *_pos;
67 }
68
69 /*
70 * move to the next line
71 */
fscache_histogram_next(struct seq_file * m,void * v,loff_t * pos)72 static void *fscache_histogram_next(struct seq_file *m, void *v, loff_t *pos)
73 {
74 (*pos)++;
75 return (unsigned long long)*pos > HZ + 2 ?
76 NULL : (void *)(unsigned long) *pos;
77 }
78
79 /*
80 * clean up after reading
81 */
fscache_histogram_stop(struct seq_file * m,void * v)82 static void fscache_histogram_stop(struct seq_file *m, void *v)
83 {
84 }
85
86 const struct seq_operations fscache_histogram_ops = {
87 .start = fscache_histogram_start,
88 .stop = fscache_histogram_stop,
89 .next = fscache_histogram_next,
90 .show = fscache_histogram_show,
91 };
92