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 18atomic_t fscache_obj_instantiate_histogram[HZ]; 19atomic_t fscache_objs_histogram[HZ]; 20atomic_t fscache_ops_histogram[HZ]; 21atomic_t fscache_retrieval_delay_histogram[HZ]; 22atomic_t fscache_retrieval_histogram[HZ]; 23 24/* 25 * display the time-taken histogram 26 */ 27static 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 */ 62static 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 */ 74static 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 */ 84static void fscache_histogram_stop(struct seq_file *m, void *v) 85{ 86} 87 88static 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 */ 98static int fscache_histogram_open(struct inode *inode, struct file *file) 99{ 100 return seq_open(file, &fscache_histogram_ops); 101} 102 103const 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