1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /* FS-Cache latency histogram
3 *
4 * Copyright (C) 2008 Red Hat, Inc. All Rights Reserved.
5 * Written by David Howells (dhowells@redhat.com)
6 */
7
8 #define FSCACHE_DEBUG_LEVEL THREAD
9 #include <linux/module.h>
10 #include <linux/proc_fs.h>
11 #include <linux/seq_file.h>
12 #include "internal.h"
13
14 atomic_t fscache_obj_instantiate_histogram[HZ];
15 atomic_t fscache_objs_histogram[HZ];
16 atomic_t fscache_ops_histogram[HZ];
17 atomic_t fscache_retrieval_delay_histogram[HZ];
18 atomic_t fscache_retrieval_histogram[HZ];
19
20 /*
21 * display the time-taken histogram
22 */
fscache_histogram_show(struct seq_file * m,void * v)23 static int fscache_histogram_show(struct seq_file *m, void *v)
24 {
25 unsigned long index;
26 unsigned n[5], t;
27
28 switch ((unsigned long) v) {
29 case 1:
30 seq_puts(m, "JIFS SECS OBJ INST OP RUNS OBJ RUNS RETRV DLY RETRIEVLS\n");
31 return 0;
32 case 2:
33 seq_puts(m, "===== ===== ========= ========= ========= ========= =========\n");
34 return 0;
35 default:
36 index = (unsigned long) v - 3;
37 n[0] = atomic_read(&fscache_obj_instantiate_histogram[index]);
38 n[1] = atomic_read(&fscache_ops_histogram[index]);
39 n[2] = atomic_read(&fscache_objs_histogram[index]);
40 n[3] = atomic_read(&fscache_retrieval_delay_histogram[index]);
41 n[4] = atomic_read(&fscache_retrieval_histogram[index]);
42 if (!(n[0] | n[1] | n[2] | n[3] | n[4]))
43 return 0;
44
45 t = (index * 1000) / HZ;
46
47 seq_printf(m, "%4lu 0.%03u %9u %9u %9u %9u %9u\n",
48 index, t, n[0], n[1], n[2], n[3], n[4]);
49 return 0;
50 }
51 }
52
53 /*
54 * set up the iterator to start reading from the first line
55 */
fscache_histogram_start(struct seq_file * m,loff_t * _pos)56 static void *fscache_histogram_start(struct seq_file *m, loff_t *_pos)
57 {
58 if ((unsigned long long)*_pos >= HZ + 2)
59 return NULL;
60 if (*_pos == 0)
61 *_pos = 1;
62 return (void *)(unsigned long) *_pos;
63 }
64
65 /*
66 * move to the next line
67 */
fscache_histogram_next(struct seq_file * m,void * v,loff_t * pos)68 static void *fscache_histogram_next(struct seq_file *m, void *v, loff_t *pos)
69 {
70 (*pos)++;
71 return (unsigned long long)*pos > HZ + 2 ?
72 NULL : (void *)(unsigned long) *pos;
73 }
74
75 /*
76 * clean up after reading
77 */
fscache_histogram_stop(struct seq_file * m,void * v)78 static void fscache_histogram_stop(struct seq_file *m, void *v)
79 {
80 }
81
82 const struct seq_operations fscache_histogram_ops = {
83 .start = fscache_histogram_start,
84 .stop = fscache_histogram_stop,
85 .next = fscache_histogram_next,
86 .show = fscache_histogram_show,
87 };
88