MDisk is not like other disk benchmarks -- its primary
purpose is not to measure basic disk subsystem performance. 
MDisk is an attempt at quantifying two parameters not measured
by any other disk benchmark that I have seen: the amount of cpu
time consumed by disk I/O; and the I/O performance of two drives
at the same time, particularly when using two physical hard
drives.

    Cpu usage is unimportant under Dos, as Dos will not allow
anything else to use the cpu during disk access.  Under a
multitasking os such as OS/2, this time can be used by other
processes.  The net effect is overall cpu performance equivalent
to what one would get under Dos with a somewhat faster cpu.
    OS/2 does not provide a direct way to measure how much cpu
time is used by a particular process/thread.  MDisk makes a
rough measurement by running a thread at idle priority which
basically counts how many times it loops during each test.  This
thread is run once by itself to obtain a baseline figure, and
again during each disk test.  The results of each run during
disk I/O is then used to caculate a percentage of available cpu
time relative to no disk I/O conditions.

    The performance of simultaneous I/O to two drives is
intended to show the benefit of advanced disk subsystems. 
Setups with multiple SCSI drives should provide some interesting
results; those with multiple ST506 type drives spread across
multiple controllers may also show benefits.
    The disk I/O thread is based on IOSTONE.  This benchmark
uses a set of test files that total about 1.5 MB, resulting in
test results that are heavily influenced by the amount of disk
caching.  Numbers obtained with cache sizes larger than the test
files will not bear any resemblence to the performance one would
get when using files significantly larger than the cache.


    Have fun!!!