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fs/fscache/histogram.c
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FS-Cache: Add use...
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/* FS-Cache latency histogram
*
* Copyright (C) 2008 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.
*/
#define FSCACHE_DEBUG_LEVEL THREAD
#include <linux/module.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include "internal.h"
atomic_t fscache_obj_instantiate_histogram[HZ];
atomic_t fscache_objs_histogram[HZ];
atomic_t fscache_ops_histogram[HZ];
atomic_t fscache_retrieval_delay_histogram[HZ];
atomic_t fscache_retrieval_histogram[HZ];
/*
* display the time-taken histogram
*/
static int fscache_histogram_show(struct seq_file *m, void *v)
{
unsigned long index;
unsigned n[5], t;
switch ((unsigned long) v) {
case 1:
seq_puts(m, "JIFS SECS OBJ INST OP RUNS OBJ RUNS "
" RETRV DLY RETRIEVLS
");
return 0;
case 2:
seq_puts(m, "===== ===== ========= ========= ========="
" ========= =========
");
return 0;
default:
index = (unsigned long) v - 3;
n[0] = atomic_read(&fscache_obj_instantiate_histogram[index]);
n[1] = atomic_read(&fscache_ops_histogram[index]);
n[2] = atomic_read(&fscache_objs_histogram[index]);
n[3] = atomic_read(&fscache_retrieval_delay_histogram[index]);
n[4] = atomic_read(&fscache_retrieval_histogram[index]);
if (!(n[0] | n[1] | n[2] | n[3] | n[4]))
return 0;
t = (index * 1000) / HZ;
seq_printf(m, "%4lu 0.%03u %9u %9u %9u %9u %9u
",
index, t, n[0], n[1], n[2], n[3], n[4]);
return 0;
}
}
/*
* set up the iterator to start reading from the first line
*/
static void *fscache_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 *fscache_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 fscache_histogram_stop(struct seq_file *m, void *v)
{
}
static const struct seq_operations fscache_histogram_ops = {
.start = fscache_histogram_start,
.stop = fscache_histogram_stop,
.next = fscache_histogram_next,
.show = fscache_histogram_show,
};
/*
* open "/proc/fs/fscache/histogram" to provide latency data
*/
static int fscache_histogram_open(struct inode *inode, struct file *file)
{
return seq_open(file, &fscache_histogram_ops);
}
const struct file_operations fscache_histogram_fops = {
.owner = THIS_MODULE,
.open = fscache_histogram_open,
.read = seq_read,
.llseek = seq_lseek,
.release = seq_release,
};
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