Process IO Top utility with Solaris DTrace

DTrace is dynamic tracing framework created by Sun Microsystems for Solaris OS. DTrace let's any system administrator or developer to get internal view of how an operating system works, find any system bottlenecks, examine a live system or process, get information on system calls, network internals and many other things. For this purpose DTrace has many providers for specific tasks. You can get list of the DTrace providers and probe function names by running following command:

# dtrace -l

DTrace also adopted to other operating systems like FreeBSD and Mac OS X. DTrace uses D Language which is subset of C programming language. You can find more information about DTrace on Sun's BigAdmin Portal.

Following example demostrates you, how easy to find the information you want on Solaris with DTrace.I wrote it to see which files are most written or read by which processes on the Solaris.

#!/usr/bin/bash
# process_io_top -  show procesess by top read/write KB I/O per file
#      Written by Levent Serinol (lserinol@gmail.com)
#      http://lserinol.blogspot.com
# Apr/14/2009
#
# USAGE: process_io_top [-s interval] [-p pid]
#   
#  -s interval  # gather and show statistics in given interval (seconds)
#  -p pid  # show read/write KB I/O just for given PID
#  -h   # show usage information
#
# eg:
# process_io_top -s 10 
#
#
#
####################################################################################
interval=5
show_pid=0
pid=0

function usage()
{
echo "
USAGE: io.sh [-s interval] [-p pid]
         -s             # set interval, default is 5 seconds
         -p pid         # pid
  eg, 
         io -p 630                # io activity of pid 630
         io -s 10                 # refresh output in every 10 seconds";
}

while getopts h:p:s:a name
do
        case $name in
        p)      show_pid=1; pid=$OPTARG ;;
        s)      interval=$OPTARG ;;
        h|?)    usage;
               exit 1
        esac
done

/usr/sbin/dtrace -Cws <( cat <<EOF

 inline int PID  = $pid;
 inline int SHOW_PID    = $show_pid;
 inline int INTERVAL    = $interval;


#pragma D option quiet
#pragma D option aggsortrev


dtrace:::BEGIN 
{
  secs = INTERVAL;
  printf("Please wait....\n");
}

io:::start 
/ (SHOW_PID == 1) && ( pid == PID) /
{
 self->rw=args[0]->b_flags & B_READ ? "R" : "W";
 @files[pid,execname,self->rw,args[2]->fi_pathname] = sum (args[0]->b_bcount);
 @total_blks[self->rw]=count();
 @total_bytes[self->rw]=sum (args[0]->b_bcount);
 self->rw=0;
}

io:::start 
/ SHOW_PID == 0 /
/* SHOW_PID == 0 && args[2]->fi_pathname != "<none>" */
{
 self->rw=args[0]->b_flags & B_READ ? "R" : "W";
 @files[pid,execname,self->rw,args[2]->fi_pathname] = sum (args[0]->b_bcount);
 @total_blks[self->rw]=count();
 @total_bytes[self->rw]=sum (args[0]->b_bcount);
 self->rw=0;
}

profile:::tick-1s
{
        secs--;
}


profile:::tick-1s
/secs == 0/
{

 trunc(@files,30);
 normalize(@files,1024);
 system("/usr/bin/clear"); 
 printf("%Y ",walltimestamp);
 printa("%s %@11d blocks, ",@total_blks);
 printa("%s %@11d bytes, ",@total_bytes);
 printf("\n%6s %-12s %3s %8s %3s\n", "PID", "CMD","R/W", "KB", "FILE");
 printa("%6d %-12.12s %1s %@10d %s\n",@files);
 secs = INTERVAL;

}
dtrace:::END
{
        trunc(@files);
}
EOF
)

You can download it here process_io_top. This scripts briefly shows you how to pass arguments from shell to DTrace. Using aggregations and sort them in reverse order by using pragma "aggsortrev". Defining probes (io:::start) more than once with different predicate conditions. Following is a sample output from process_io_top script.