IO script

[Wenji Huang <wenji dot huang at oracle dot com>]

Hi,

 Just as discussion at last conference call, Dtrace provides good 
toolkit for users. see            

      http://www.opensolaris.org/os/community/dtrace/dtracetoolkit/
      http://prefetch.net/articles/solaris.dtracetopten.html

 If systemtap has same facility, it is very helpful to widen the use.

 Based on idea from Dtrace, I created two scripts which can illustrate 
disk I/O status.

 Please kindly review it. If possible, we maybe collect/create some 
useful stap scripts as toolkit embedded in source.

Regards,
Wenji

#!/usr/bin/env stap 
#
# Copyright (C) 2007 Oracle Corp.
#
# provide the percentage of random and sequential I/O on the system
#
# bought idea from Dtrace
#
# GNU General Public License (GPL); either version 2, or (at your option) any
# later version.
#
#
# Usage:
#  ./iopattern.stp 
#

global disk_loc
global disk_r,disk_w,disk_ran,disk_cnt,disk_min,disk_max

probe ioblock.end{

	bytes_done = bytes_done > size ? bytes_done:size

	/*WRITE 1*/
        disk_r += (rw & 1) ? 0 : bytes_done
        disk_w += (rw & 1) ? bytes_done: 0
       
        /*Not precise at first time, disk_ran = 0 */
       	disk_ran += (sector*512 == disk_loc[devname]) ? 0 : 1
        disk_cnt++

       	disk_min = disk_min == 0 ? bytes_done :(disk_min > bytes_done ? bytes_done : disk_min);
       	disk_max = disk_max < bytes_done ? bytes_done : disk_max;

        /*record the location*/
	disk_loc[devname] += sector*512 + bytes_done
}

probe begin {
        printf("%4s %4s %6s %6s %6s %6s %8s %8s\n",
            "%RAN", "%SEQ", "COUNT", "MIN", "MAX", "AVG", "R(Kb)", "W(Kb)")

}

probe timer.ms(5000)
{
        /* calcluate average performance */
        disk_avg = disk_cnt > 0 ? (disk_r + disk_w) / disk_cnt : 0

        /* convert to Kbytes */
        disk_r /= 1024
        disk_w /= 1024

        /* convert to percentage */
        disk_ran = disk_cnt == 0 ? 0 : (disk_ran * 100) / disk_cnt
        disk_seq = disk_cnt == 0 ? 0 : 100 - disk_ran


        printf("%4d %4d %6d %6d %6d %6d %8d %8d\n",
            disk_ran, disk_seq, disk_cnt, disk_min, disk_max, disk_avg,
            disk_r, disk_w)

        /* clear data */
        disk_min = 0
        disk_max = 0
        disk_cnt = 0
        disk_ran = 0
        disk_r = 0
        disk_w = 0
}

#!/usr/bin/env stap 
#
# Copyright (C) 2007 Oracle Corp.
#
# Get the rough status of seeking in block I/O 
#
# bought idea from Dtrace
#
# GNU General Public License (GPL); either version 2, or (at your option) any
# later version.
#
#
# Usage:
#  ./seeksize.stp 
#

global disk_head
global disk_distance

probe ioblock.request{
	/*calculate the movement distance*/
	distance = sector - disk_head[devname] > 0 ? sector-disk_head[devname] : disk_head[devname]-sector
	if (disk_head[devname] != 0 ) /*skip the first time, no last head position*/
		disk_distance[devname] <<< distance
	disk_head[devname] = size/512 + sector
}

probe begin {
	print("Collecting data... Type Ctrl-C to exit and display results\n")
}	

probe end {
        foreach ([name] in disk_distance) {
                printf("Device %s\n", name)
                printf("Count:   %d movements\n", @count(disk_distance[name]))
                printf("Sum:     %d sectors\n", @sum(disk_distance[name]))
                printf("Average: %d sectors\n", @avg(disk_distance[name]))
                printf("Min:     %d sectors\n", @min(disk_distance[name]))
                printf("Max:     %d sectors\n", @max(disk_distance[name]))
                print("\nSeek by sectors \n")
                print(@hist_log(disk_distance[name]))
                printf("-------------------------------------------------------\n\n");
	}
}