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ProfilingTheStack
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For all forms of <a href="Profiling">Profiling</a>, you can gather counts for all functions on the stack, not just the currently executing function. To do so, compile your program with <tt>-profile-stack true</tt>. For example, suppose that <tt>list-rev.sml</tt> contains the following. <p>
<pre class=code><B><FONT COLOR="#A020F0">fun </FONT></B><B><FONT COLOR="#0000FF"><B><I><FONT COLOR="#000000">append</FONT></I></B></FONT></B> (l1, l2) <B><FONT COLOR="#5F9EA0">=</FONT></B>
<B><FONT COLOR="#A020F0">case</FONT></B> l1 <B><FONT COLOR="#A020F0">of</FONT></B>
[] <B><FONT COLOR="#5F9EA0">=</FONT></B><B><FONT COLOR="#5F9EA0">></FONT></B> l2
<B><FONT COLOR="#5F9EA0">|</FONT></B> x <B><FONT COLOR="#5F9EA0">::</FONT></B> l1 <B><FONT COLOR="#5F9EA0">=</FONT></B><B><FONT COLOR="#5F9EA0">></FONT></B> x <B><FONT COLOR="#5F9EA0">::</FONT></B> append (l1, l2)
<B><FONT COLOR="#A020F0">fun </FONT></B><B><FONT COLOR="#0000FF"><B><I><FONT COLOR="#000000">rev</FONT></I></B></FONT></B> l <B><FONT COLOR="#5F9EA0">=</FONT></B>
<B><FONT COLOR="#A020F0">case</FONT></B> l <B><FONT COLOR="#A020F0">of</FONT></B>
[] <B><FONT COLOR="#5F9EA0">=</FONT></B><B><FONT COLOR="#5F9EA0">></FONT></B> []
<B><FONT COLOR="#5F9EA0">|</FONT></B> x <B><FONT COLOR="#5F9EA0">::</FONT></B> l <B><FONT COLOR="#5F9EA0">=</FONT></B><B><FONT COLOR="#5F9EA0">></FONT></B> append (rev l, [x])
<B><FONT COLOR="#A020F0">val</FONT></B> l <B><FONT COLOR="#5F9EA0">=</FONT></B> List.tabulate (1000, <B><FONT COLOR="#A020F0">fn</FONT></B> i <B><FONT COLOR="#5F9EA0">=</FONT></B><B><FONT COLOR="#5F9EA0">></FONT></B> i)
<B><FONT COLOR="#A020F0">val</FONT></B> _ <B><FONT COLOR="#5F9EA0">=</FONT></B> 1 <B><FONT COLOR="#5F9EA0">+</FONT></B> <B><FONT COLOR="#5F9EA0">hd</FONT></B> (rev l)
</PRE>
</p>
<p>
Compile with stack profiling and then run the program.
<pre>% mlton -profile alloc -profile-stack true list-rev.sml
% ./list-rev
</pre>
</p>
<p>
Display the profiling data.
</p>
<pre>% mlprof -show-line true list-rev mlmon.out
6,030,136 bytes allocated (108,336 bytes by GC)
function cur stack GC
----------------------- ----- ----- ----
append list-rev.sml: 1 97.6% 97.6% 1.4%
<gc> 1.8% 0.0% 1.8%
<main> 0.4% 98.2% 1.8%
rev list-rev.sml: 6 0.2% 97.6% 1.8%
</pre><p>
In the above table, we see that <tt>rev</tt>, defined on line 6 of <tt>list-rev.sml</tt>, is only responsible for 0.2% of the allocation, but is on the stack while 97.6% of the allocation is done by the user program and while 1.8% of the allocation is done by the garbage collector.
</p>
<p>
The run-time performance impact of <tt>-profile-stack true</tt> can be noticeable since there is some extra bookkeeping at every nontail call and return.
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Last edited on 2005-12-02 00:47:48 by <span title="ppp-71-139-183-221.dsl.snfc21.pacbell.net"><a href="StephenWeeks">StephenWeeks</a></span>.
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