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kernel/linux-imx6_3.14.28/fs/fscache/histogram.c 2.79 KB
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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,
  };