| David Howells | 7394daa | 2009-04-03 16:42:37 +0100 | [diff] [blame] | 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 | }; |