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<H1><A NAME="SECTION0012200000000000000000">
10.2 How Is This Profiler Different From The Old Profiler?</A>
</H1>
<A NAME="Profiler_Changes"></A>
<P>
(This section is of historical importance only; the old profiler
discussed here was last seen in Python 1.1.)

<P>
The big changes from old profiling module are that you get more
information, and you pay less CPU time.  It's not a trade-off, it's a
trade-up.

<P>
To be specific:

<P>
<DL>
<DT><STRONG>Bugs removed:</STRONG></DT>
<DD>Local stack frame is no longer molested, execution time is now charged
to correct functions.

<P>
</DD>
<DT><STRONG>Accuracy increased:</STRONG></DT>
<DD>Profiler execution time is no longer charged to user's code,
calibration for platform is supported, file reads are not done <em>by</em>
profiler <em>during</em> profiling (and charged to user's code!).

<P>
</DD>
<DT><STRONG>Speed increased:</STRONG></DT>
<DD>Overhead CPU cost was reduced by more than a factor of two (perhaps a
factor of five), lightweight profiler module is all that must be
loaded, and the report generating module (<tt class="module">pstats</tt>) is not needed
during profiling.

<P>
</DD>
<DT><STRONG>Recursive functions support:</STRONG></DT>
<DD>Cumulative times in recursive functions are correctly calculated;
recursive entries are counted.

<P>
</DD>
<DT><STRONG>Large growth in report generating UI:</STRONG></DT>
<DD>Distinct profiles runs can be added together forming a comprehensive
report; functions that import statistics take arbitrary lists of
files; sorting criteria is now based on keywords (instead of 4 integer
options); reports shows what functions were profiled as well as what
profile file was referenced; output format has been improved.

<P>
</DD>
</DL>

<P>

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	54
	55	<H1><A NAME="SECTION0012200000000000000000">
	56	10.2 How Is This Profiler Different From The Old Profiler?</A>
	57	</H1>
	58	<A NAME="Profiler_Changes"></A>
	59	<P>
	60	(This section is of historical importance only; the old profiler
	61	discussed here was last seen in Python 1.1.)
	62
	63	<P>
	64	The big changes from old profiling module are that you get more
65	information, and you pay less CPU time. It's not a trade-off, it's a
66	trade-up.
67
68	<P>
69	To be specific:
70
71	<P>
72	<DL>
73	<DT><STRONG>Bugs removed:</STRONG></DT>
74	<DD>Local stack frame is no longer molested, execution time is now charged
75	to correct functions.
76
77	<P>
78	</DD>
79	<DT><STRONG>Accuracy increased:</STRONG></DT>
80	<DD>Profiler execution time is no longer charged to user's code,
81	calibration for platform is supported, file reads are not done <em>by</em>
82	profiler <em>during</em> profiling (and charged to user's code!).
83
84	<P>
85	</DD>
86	<DT><STRONG>Speed increased:</STRONG></DT>
87	<DD>Overhead CPU cost was reduced by more than a factor of two (perhaps a
88	factor of five), lightweight profiler module is all that must be
89	loaded, and the report generating module (<tt class="module">pstats</tt>) is not needed
90	during profiling.
91
92	<P>
93	</DD>
94	<DT><STRONG>Recursive functions support:</STRONG></DT>
95	<DD>Cumulative times in recursive functions are correctly calculated;
96	recursive entries are counted.
97
98	<P>
99	</DD>
100	<DT><STRONG>Large growth in report generating UI:</STRONG></DT>
101	<DD>Distinct profiles runs can be added together forming a comprehensive
102	report; functions that import statistics take arbitrary lists of
103	files; sorting criteria is now based on keywords (instead of 4 integer
104	options); reports shows what functions were profiled as well as what
105	profile file was referenced; output format has been improved.
106
107	<P>
108	</DD>
109	</DL>
110
111	<P>
112
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