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<h2>13.4 Why is <code>__dpmi_int</code> so heavily used?</h2>

<p><em><strong>Q</strong>: I've profiled my program and found that the routine which takes
60% of the running time is some obscure library function called
<code>__dpmi_int</code>.  Can't you guys get your library right?</em>

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<p><em><strong>Q</strong>: What is the <code>__dj_movedata</code> function for, and why does it
take such a large proportion of my program's running time?</em>

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<p><strong>A</strong>:  Does your program use I/O or other real-mode services (like BIOS)
extensively?  All those services are invoked through a DPMI function call
which is issued by <code>__dpmi_int</code>.  The sibling function
<code>__dj_movedata</code> moves data between the <dfn>transfer buffer</dfn>
(see <a href="faq14_4.html">what is the transfer buffer</a>) and your program, e.g., when it reads or writes disk files. 
So what the profile really says is that the running time of your program
is governed by time-consuming operations such as disk I/O.

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