iostat for process names

Problem

We want to know which processes are doing the most IO on the system.

Script

global reads, writes, total_io

probe kernel.function("vfs_read") {
    reads[execname()] += $count
}

probe kernel.function("vfs_write") {
    writes[execname()] += $count
}

# print top 10 IO processes every 5 seconds
probe timer.s(5) {
    foreach (name in writes)
        total_io[name] += writes[name]
    foreach (name in reads)
        total_io[name] += reads[name]
    printf ("%16s\t%10s\t%10s\n", "Process", "KB Read", "KB Written")
    foreach (name in total_io- limit 10)
        printf("%16s\t%10d\t%10d\n", name,
               reads[name]/1024, writes[name]/1024)
    delete reads
    delete writes
    delete total_io
    print("\n")
}

Output

         Process           KB Read      KB Written
            Xvnc             16831               3
            grep              5754               3
            sort              2046               0
           xterm               718              19
             twm               610              15
       vncserver               153               0
            sshd               128               0
            bash                52               0
             cat                33               0
            yast                29               0

This script is based on SystemTap High-level presentation from Linux World San Francisco August 2006