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#!/bin/bash
#
# Oracle Linux DTrace.
# Copyright (c) 2025, Oracle and/or its affiliates. All rights reserved.
# Licensed under the Universal Permissive License v 1.0 as shown at
# http://oss.oracle.com/licenses/upl.
#
#------------------------------------------------------------------------------
# This example embeds a DTrace script in a bash script. The bash script
# is used to set the variables needed in the D script.
#
# fsact -- Display cumulative read and write activity across a file
# system device
#
# Usage: fsact [<filesystem>]
#------------------------------------------------------------------------------
#------------------------------------------------------------------------------
# If no file system is specified, assume /
#------------------------------------------------------------------------------
[ $# -eq 1 ] && FSNAME=$1 || FSNAME="/"
[ ! -e $FSNAME ] && echo "$FSNAME not found" && exit 1
#------------------------------------------------------------------------------
# Determine the mountpoint, major and minor numbers, and file system size.
#------------------------------------------------------------------------------
MNTPNT=$(df $FSNAME | gawk '{ getline; print $1; exit }')
MAJOR=$(printf "%d\n" 0x$(stat -Lc "%t" $MNTPNT))
MINOR=$(printf "%d\n" 0x$(stat -Lc "%T" $MNTPNT))
FSSIZE=$(stat -fc "%b" $FSNAME)
#------------------------------------------------------------------------------
# Run the embedded D script.
#------------------------------------------------------------------------------
sudo dtrace -qs /dev/stdin << EOF
/*
* DESCRIPTION
* The io:::done probe from the io provider is used to get read and write
* statistics. In particular, the id of the block that is accessed for
* the read or write operation.
*/
BEGIN
{
printf("Show how often blocks are accessed in read and write operations\n");
printf("The statistics are updated every 5 seconds\n");
printf("The block IDs are normalized to a scale from 0 to 10\n");
printf("The file system is %s\n","$FSNAME");
printf("The mount point is %s\n","$MNTPNT");
printf("The file system size is %s bytes\n","$FSSIZE");
}
/*
* This probe fires after an I/O request has been fulfilled. The
* done probe fires after the I/O completes, but before completion
* processing has been performed on the buffer.
*
* A pointer to structure devinfo_t is in args[1]. This is used
* to get the major and minor number of the device.
*
* A pointer to structure bufinfo_t is in args[0]. This is used
* to get the flags and the block number.
*/
io:::done
/ args[1]->dev_major == $MAJOR && args[1]->dev_minor == $MINOR /
{
/*
* Check if B_READ has been set and assign a string to io_type
* based on the outcome of the check. This string is used as
* the key in aggregation io_stats.
*/
io_type = args[0]->b_flags & B_READ ? "READ" : "WRITE";
/*
* Structure member b_lblkno identifies which logical block on the
* device is to be accessed. Normalize thise block number as an
* integer in the range 0 to 10.
*/
blkno = (args[0]->b_blkno)*10/$FSSIZE;
/*
* Aggregate blkno linearly over the range 0 to 10 in steps of 1.
*/
@io_stats[io_type] = lquantize(blkno,0,10,1)
}
/*
* Fires every 5 seconds.
*/
profile:::tick-5s
{
printf("%Y\n",walltimestamp);
/*
* Display the contents of the aggregation.
*/
printa("%s\n%@d\n",@io_stats);
/*
* Reset the aggregation every time this probe fires
*/
clear(@io_stats);
}
/*
* Fires every 21 seconds. Since exit() is called, the tracing terminates
* the first time this probe fires and the clause is executed.
*/
profile:::tick-21s
{
printf("Tracing is terminated now\n");
exit(0);
}
EOF
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