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7394daa8c6
Make FS-Cache create its /proc interface and present various statistical information through it. Also provide the functions for updating this information. These features are enabled by: CONFIG_FSCACHE_PROC CONFIG_FSCACHE_STATS CONFIG_FSCACHE_HISTOGRAM The /proc directory for FS-Cache is also exported so that caching modules can add their own statistics there too. The FS-Cache module is loadable at this point, and the statistics files can be examined by userspace: cat /proc/fs/fscache/stats cat /proc/fs/fscache/histogram Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
109 lines
2.8 KiB
C
109 lines
2.8 KiB
C
/* FS-Cache latency histogram
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*
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* Copyright (C) 2008 Red Hat, Inc. All Rights Reserved.
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* Written by David Howells (dhowells@redhat.com)
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public Licence
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* as published by the Free Software Foundation; either version
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* 2 of the Licence, or (at your option) any later version.
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*/
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#define FSCACHE_DEBUG_LEVEL THREAD
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#include <linux/module.h>
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#include <linux/proc_fs.h>
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#include <linux/seq_file.h>
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#include "internal.h"
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atomic_t fscache_obj_instantiate_histogram[HZ];
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atomic_t fscache_objs_histogram[HZ];
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atomic_t fscache_ops_histogram[HZ];
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atomic_t fscache_retrieval_delay_histogram[HZ];
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atomic_t fscache_retrieval_histogram[HZ];
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/*
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* display the time-taken histogram
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*/
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static int fscache_histogram_show(struct seq_file *m, void *v)
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{
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unsigned long index;
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unsigned n[5], t;
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switch ((unsigned long) v) {
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case 1:
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seq_puts(m, "JIFS SECS OBJ INST OP RUNS OBJ RUNS "
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" RETRV DLY RETRIEVLS\n");
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return 0;
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case 2:
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seq_puts(m, "===== ===== ========= ========= ========="
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" ========= =========\n");
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return 0;
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default:
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index = (unsigned long) v - 3;
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n[0] = atomic_read(&fscache_obj_instantiate_histogram[index]);
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n[1] = atomic_read(&fscache_ops_histogram[index]);
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n[2] = atomic_read(&fscache_objs_histogram[index]);
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n[3] = atomic_read(&fscache_retrieval_delay_histogram[index]);
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n[4] = atomic_read(&fscache_retrieval_histogram[index]);
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if (!(n[0] | n[1] | n[2] | n[3] | n[4]))
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return 0;
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t = (index * 1000) / HZ;
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seq_printf(m, "%4lu 0.%03u %9u %9u %9u %9u %9u\n",
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index, t, n[0], n[1], n[2], n[3], n[4]);
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return 0;
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}
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}
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/*
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* set up the iterator to start reading from the first line
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*/
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static void *fscache_histogram_start(struct seq_file *m, loff_t *_pos)
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{
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if ((unsigned long long)*_pos >= HZ + 2)
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return NULL;
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if (*_pos == 0)
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*_pos = 1;
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return (void *)(unsigned long) *_pos;
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}
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/*
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* move to the next line
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*/
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static void *fscache_histogram_next(struct seq_file *m, void *v, loff_t *pos)
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{
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(*pos)++;
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return (unsigned long long)*pos > HZ + 2 ?
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NULL : (void *)(unsigned long) *pos;
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}
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/*
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* clean up after reading
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*/
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static void fscache_histogram_stop(struct seq_file *m, void *v)
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{
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}
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static const struct seq_operations fscache_histogram_ops = {
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.start = fscache_histogram_start,
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.stop = fscache_histogram_stop,
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.next = fscache_histogram_next,
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.show = fscache_histogram_show,
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};
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/*
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* open "/proc/fs/fscache/histogram" to provide latency data
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*/
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static int fscache_histogram_open(struct inode *inode, struct file *file)
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{
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return seq_open(file, &fscache_histogram_ops);
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}
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const struct file_operations fscache_histogram_fops = {
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.owner = THIS_MODULE,
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.open = fscache_histogram_open,
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.read = seq_read,
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.llseek = seq_lseek,
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.release = seq_release,
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};
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