original development tree for Linux kernel GTP module; now long in mainline.
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/* CacheFiles statistics
*
* Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public Licence
* as published by the Free Software Foundation; either version
* 2 of the Licence, or (at your option) any later version.
*/
#include <linux/module.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include "internal.h"
atomic_t cachefiles_lookup_histogram[HZ];
atomic_t cachefiles_mkdir_histogram[HZ];
atomic_t cachefiles_create_histogram[HZ];
/*
* display the latency histogram
*/
static int cachefiles_histogram_show(struct seq_file *m, void *v)
{
unsigned long index;
unsigned x, y, z, t;
switch ((unsigned long) v) {
case 1:
seq_puts(m, "JIFS SECS LOOKUPS MKDIRS CREATES\n");
return 0;
case 2:
seq_puts(m, "===== ===== ========= ========= =========\n");
return 0;
default:
index = (unsigned long) v - 3;
x = atomic_read(&cachefiles_lookup_histogram[index]);
y = atomic_read(&cachefiles_mkdir_histogram[index]);
z = atomic_read(&cachefiles_create_histogram[index]);
if (x == 0 && y == 0 && z == 0)
return 0;
t = (index * 1000) / HZ;
seq_printf(m, "%4lu 0.%03u %9u %9u %9u\n", index, t, x, y, z);
return 0;
}
}
/*
* set up the iterator to start reading from the first line
*/
static void *cachefiles_histogram_start(struct seq_file *m, loff_t *_pos)
{
if ((unsigned long long)*_pos >= HZ + 2)
return NULL;
if (*_pos == 0)
*_pos = 1;
return (void *)(unsigned long) *_pos;
}
/*
* move to the next line
*/
static void *cachefiles_histogram_next(struct seq_file *m, void *v, loff_t *pos)
{
(*pos)++;
return (unsigned long long)*pos > HZ + 2 ?
NULL : (void *)(unsigned long) *pos;
}
/*
* clean up after reading
*/
static void cachefiles_histogram_stop(struct seq_file *m, void *v)
{
}
static const struct seq_operations cachefiles_histogram_ops = {
.start = cachefiles_histogram_start,
.stop = cachefiles_histogram_stop,
.next = cachefiles_histogram_next,
.show = cachefiles_histogram_show,
};
/*
* open "/proc/fs/cachefiles/XXX" which provide statistics summaries
*/
static int cachefiles_histogram_open(struct inode *inode, struct file *file)
{
return seq_open(file, &cachefiles_histogram_ops);
}
static const struct file_operations cachefiles_histogram_fops = {
.owner = THIS_MODULE,
.open = cachefiles_histogram_open,
.read = seq_read,
.llseek = seq_lseek,
.release = seq_release,
};
/*
* initialise the /proc/fs/cachefiles/ directory
*/
int __init cachefiles_proc_init(void)
{
_enter("");
if (!proc_mkdir("fs/cachefiles", NULL))
goto error_dir;
if (!proc_create("fs/cachefiles/histogram", S_IFREG | 0444, NULL,
&cachefiles_histogram_fops))
goto error_histogram;
_leave(" = 0");
return 0;
error_histogram:
remove_proc_entry("fs/cachefiles", NULL);
error_dir:
_leave(" = -ENOMEM");
return -ENOMEM;
}
/*
* clean up the /proc/fs/cachefiles/ directory
*/
void cachefiles_proc_cleanup(void)
{
remove_proc_entry("fs/cachefiles/histogram", NULL);
remove_proc_entry("fs/cachefiles", NULL);
}