Assessing overall disk I/O with the vmstat command

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The technique just discussed can also be used to assess the disk I/O load generated by a program.

If the system is otherwise idle, the following sequence: 
# vmstat -s >statout
# testpgm
# sync
# vmstat -s >> statout
# egrep "ins|outs" statout
yields a before and after picture of the cumulative disk activity counts, such as: 
     5698 page ins
     5012 page outs
        0 paging space page ins
       32 paging space page outs
     6671 page ins
     5268 page outs
        8 paging space page ins
      225 paging space page outs
During the period when this command (a large C compile) was running, the system read a total of 981 pages (8 from paging space) and wrote a total of 449 pages (193 to paging space).