[OpenSPARC-T2-SAM] / sam-t2 / devtools / v8plus / html / python / lib / node464.html

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<html>
<head>
<link rel="STYLESHEET" href="lib.css" type='text/css' />
<link rel="SHORTCUT ICON" href="../icons/pyfav.png" type="image/png" />
<link rel='start' href='../index.html' title='Python Documentation Index' />
<link rel="first" href="lib.html" title='Python Library Reference' />
<link rel='contents' href='contents.html' title="Contents" />
<link rel='index' href='genindex.html' title='Index' />
<link rel='last' href='about.html' title='About this document...' />
<link rel='help' href='about.html' title='About this document...' />
<link rel="next" href="node465.html" />
<link rel="prev" href="module-timeit.html" />
<link rel="parent" href="module-timeit.html" />
<link rel="next" href="node465.html" />
<meta name='aesop' content='information' />
<title>10.10.1 Command Line Interface</title>
</head>
<body>
<DIV CLASS="navigation">
<div id='top-navigation-panel' xml:id='top-navigation-panel'>
<table align="center" width="100%" cellpadding="0" cellspacing="2">
<tr>
<td class='online-navigation'><a rel="prev" title="10.10 timeit  "
  href="module-timeit.html"><img src='../icons/previous.png'
  border='0' height='32'  alt='Previous Page' width='32' /></A></td>
<td class='online-navigation'><a rel="parent" title="10.10 timeit  "
  href="module-timeit.html"><img src='../icons/up.png'
  border='0' height='32'  alt='Up One Level' width='32' /></A></td>
<td class='online-navigation'><a rel="next" title="10.10.2 Examples"
  href="node465.html"><img src='../icons/next.png'
  border='0' height='32'  alt='Next Page' width='32' /></A></td>
<td align="center" width="100%">Python Library Reference</td>
<td class='online-navigation'><a rel="contents" title="Table of Contents"
  href="contents.html"><img src='../icons/contents.png'
  border='0' height='32'  alt='Contents' width='32' /></A></td>
<td class='online-navigation'><a href="modindex.html" title="Module Index"><img src='../icons/modules.png'
  border='0' height='32'  alt='Module Index' width='32' /></a></td>
<td class='online-navigation'><a rel="index" title="Index"
  href="genindex.html"><img src='../icons/index.png'
  border='0' height='32'  alt='Index' width='32' /></A></td>
</tr></table>
<div class='online-navigation'>
<b class="navlabel">Previous:</b>
<a class="sectref" rel="prev" href="module-timeit.html">10.10 timeit  </A>
<b class="navlabel">Up:</b>
<a class="sectref" rel="parent" href="module-timeit.html">10.10 timeit  </A>
<b class="navlabel">Next:</b>
<a class="sectref" rel="next" href="node465.html">10.10.2 Examples</A>
</div>
<hr /></div>
</DIV>
<!--End of Navigation Panel-->

<H2><A NAME="SECTION00121010000000000000000">
10.10.1 Command Line Interface</A>
</H2>

<P>
When called as a program from the command line, the following form is used:

<P>
<div class="verbatim"><pre>
python timeit.py [-n N] [-r N] [-s S] [-t] [-c] [-h] [statement ...]
</pre></div>

<P>
where the following options are understood:

<P>
<DL>
<DT><STRONG>-n N/<b class="programopt">--number=N</b></STRONG></DT>
<DD>how many times to execute 'statement'
</DD>
<DT><STRONG>-r N/<b class="programopt">--repeat=N</b></STRONG></DT>
<DD>how many times to repeat the timer (default 3)
</DD>
<DT><STRONG>-s S/<b class="programopt">--setup=S</b></STRONG></DT>
<DD>statement to be executed once initially (default
<code>'pass'</code>)
</DD>
<DT><STRONG>-t/<b class="programopt">--time</b></STRONG></DT>
<DD>use <tt class="function">time.time()</tt>
(default on all platforms but Windows)
</DD>
<DT><STRONG>-c/<b class="programopt">--clock</b></STRONG></DT>
<DD>use <tt class="function">time.clock()</tt> (default on Windows)
</DD>
<DT><STRONG>-v/<b class="programopt">--verbose</b></STRONG></DT>
<DD>print raw timing results; repeat for more digits
precision
</DD>
<DT><STRONG>-h/<b class="programopt">--help</b></STRONG></DT>
<DD>print a short usage message and exit
</DD>
</DL>

<P>
A multi-line statement may be given by specifying each line as a
separate statement argument; indented lines are possible by enclosing
an argument in quotes and using leading spaces.  Multiple
<b class="programopt">-s</b> options are treated similarly.

<P>
If <b class="programopt">-n</b> is not given, a suitable number of loops is
calculated by trying successive powers of 10 until the total time is
at least 0.2 seconds.

<P>
The default timer function is platform dependent.  On Windows,
<tt class="function">time.clock()</tt> has microsecond granularity but
<tt class="function">time.time()</tt>'s granularity is 1/60th of a second; on <span class="Unix">Unix</span>,
<tt class="function">time.clock()</tt> has 1/100th of a second granularity and
<tt class="function">time.time()</tt> is much more precise.  On either platform, the
default timer functions measure wall clock time, not the CPU time.
This means that other processes running on the same computer may
interfere with the timing.  The best thing to do when accurate timing
is necessary is to repeat the timing a few times and use the best
time.  The <b class="programopt">-r</b> option is good for this; the default of 3
repetitions is probably enough in most cases.  On <span class="Unix">Unix</span>, you can use
<tt class="function">time.clock()</tt> to measure CPU time.

<P>
<div class="note"><b class="label">Note:</b>
There is a certain baseline overhead associated with executing a
  pass statement.  The code here doesn't try to hide it, but you
  should be aware of it.  The baseline overhead can be measured by
  invoking the program without arguments.
</div>

<P>
The baseline overhead differs between Python versions!  Also, to
fairly compare older Python versions to Python 2.3, you may want to
use Python's <b class="programopt">-O</b> option for the older versions to avoid
timing <code>SET_LINENO</code> instructions.

<P>

<DIV CLASS="navigation">
<div class='online-navigation'>
<p></p><hr />
<table align="center" width="100%" cellpadding="0" cellspacing="2">
<tr>
<td class='online-navigation'><a rel="prev" title="10.10 timeit  "
  href="module-timeit.html"><img src='../icons/previous.png'
  border='0' height='32'  alt='Previous Page' width='32' /></A></td>
<td class='online-navigation'><a rel="parent" title="10.10 timeit  "
  href="module-timeit.html"><img src='../icons/up.png'
  border='0' height='32'  alt='Up One Level' width='32' /></A></td>
<td class='online-navigation'><a rel="next" title="10.10.2 Examples"
  href="node465.html"><img src='../icons/next.png'
  border='0' height='32'  alt='Next Page' width='32' /></A></td>
<td align="center" width="100%">Python Library Reference</td>
<td class='online-navigation'><a rel="contents" title="Table of Contents"
  href="contents.html"><img src='../icons/contents.png'
  border='0' height='32'  alt='Contents' width='32' /></A></td>
<td class='online-navigation'><a href="modindex.html" title="Module Index"><img src='../icons/modules.png'
  border='0' height='32'  alt='Module Index' width='32' /></a></td>
<td class='online-navigation'><a rel="index" title="Index"
  href="genindex.html"><img src='../icons/index.png'
  border='0' height='32'  alt='Index' width='32' /></A></td>
</tr></table>
<div class='online-navigation'>
<b class="navlabel">Previous:</b>
<a class="sectref" rel="prev" href="module-timeit.html">10.10 timeit  </A>
<b class="navlabel">Up:</b>
<a class="sectref" rel="parent" href="module-timeit.html">10.10 timeit  </A>
<b class="navlabel">Next:</b>
<a class="sectref" rel="next" href="node465.html">10.10.2 Examples</A>
</div>
</div>
<hr />
<span class="release-info">Release 2.4.2, documentation updated on 28 September 2005.</span>
</DIV>
<!--End of Navigation Panel-->
<ADDRESS>
See <i><a href="about.html">About this document...</a></i> for information on suggesting changes.
</ADDRESS>
</BODY>
</HTML>
Commit	Line	Data
920dae64 AT	1	<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
	2	<html>
	3	<head>
	4	<link rel="STYLESHEET" href="lib.css" type='text/css' />
	5	<link rel="SHORTCUT ICON" href="../icons/pyfav.png" type="image/png" />
	6	<link rel='start' href='../index.html' title='Python Documentation Index' />
	7	<link rel="first" href="lib.html" title='Python Library Reference' />
	8	<link rel='contents' href='contents.html' title="Contents" />
	9	<link rel='index' href='genindex.html' title='Index' />
	10	<link rel='last' href='about.html' title='About this document...' />
	11	<link rel='help' href='about.html' title='About this document...' />
	12	<link rel="next" href="node465.html" />
	13	<link rel="prev" href="module-timeit.html" />
	14	<link rel="parent" href="module-timeit.html" />
	15	<link rel="next" href="node465.html" />
	16	<meta name='aesop' content='information' />
	17	<title>10.10.1 Command Line Interface</title>
	18	</head>
	19	<body>
	20	<DIV CLASS="navigation">
	21	<div id='top-navigation-panel' xml:id='top-navigation-panel'>
	22	<table align="center" width="100%" cellpadding="0" cellspacing="2">
	23	<tr>
	24	<td class='online-navigation'><a rel="prev" title="10.10 timeit "
	25	href="module-timeit.html"><img src='../icons/previous.png'
	26	border='0' height='32' alt='Previous Page' width='32' /></A></td>
	27	<td class='online-navigation'><a rel="parent" title="10.10 timeit "
	28	href="module-timeit.html"><img src='../icons/up.png'
	29	border='0' height='32' alt='Up One Level' width='32' /></A></td>
	30	<td class='online-navigation'><a rel="next" title="10.10.2 Examples"
	31	href="node465.html"><img src='../icons/next.png'
	32	border='0' height='32' alt='Next Page' width='32' /></A></td>
	33	<td align="center" width="100%">Python Library Reference</td>
	34	<td class='online-navigation'><a rel="contents" title="Table of Contents"
	35	href="contents.html"><img src='../icons/contents.png'
	36	border='0' height='32' alt='Contents' width='32' /></A></td>
	37	<td class='online-navigation'><a href="modindex.html" title="Module Index"><img src='../icons/modules.png'
	38	border='0' height='32' alt='Module Index' width='32' /></a></td>
	39	<td class='online-navigation'><a rel="index" title="Index"
	40	href="genindex.html"><img src='../icons/index.png'
	41	border='0' height='32' alt='Index' width='32' /></A></td>
	42	</tr></table>
	43	<div class='online-navigation'>
	44	<b class="navlabel">Previous:</b>
	45	<a class="sectref" rel="prev" href="module-timeit.html">10.10 timeit </A>
	46	<b class="navlabel">Up:</b>
	47	<a class="sectref" rel="parent" href="module-timeit.html">10.10 timeit </A>
	48	<b class="navlabel">Next:</b>
	49	<a class="sectref" rel="next" href="node465.html">10.10.2 Examples</A>
	50	</div>
	51	<hr /></div>
	52	</DIV>
	53	<!--End of Navigation Panel-->
	54
	55	<H2><A NAME="SECTION00121010000000000000000">
	56	10.10.1 Command Line Interface</A>
	57	</H2>
	58
	59	<P>
	60	When called as a program from the command line, the following form is used:
	61
	62	<P>
	63	<div class="verbatim"><pre>
	64	python timeit.py [-n N] [-r N] [-s S] [-t] [-c] [-h] [statement ...]
65	</pre></div>
66
67	<P>
68	where the following options are understood:
69
70	<P>
71	<DL>
72	<DT><STRONG>-n N/<b class="programopt">--number=N</b></STRONG></DT>
73	<DD>how many times to execute 'statement'
74	</DD>
75	<DT><STRONG>-r N/<b class="programopt">--repeat=N</b></STRONG></DT>
76	<DD>how many times to repeat the timer (default 3)
77	</DD>
78	<DT><STRONG>-s S/<b class="programopt">--setup=S</b></STRONG></DT>
79	<DD>statement to be executed once initially (default
80	<code>'pass'</code>)
81	</DD>
82	<DT><STRONG>-t/<b class="programopt">--time</b></STRONG></DT>
83	<DD>use <tt class="function">time.time()</tt>
84	(default on all platforms but Windows)
85	</DD>
86	<DT><STRONG>-c/<b class="programopt">--clock</b></STRONG></DT>
87	<DD>use <tt class="function">time.clock()</tt> (default on Windows)
88	</DD>
89	<DT><STRONG>-v/<b class="programopt">--verbose</b></STRONG></DT>
90	<DD>print raw timing results; repeat for more digits
91	precision
92	</DD>
93	<DT><STRONG>-h/<b class="programopt">--help</b></STRONG></DT>
94	<DD>print a short usage message and exit
95	</DD>
96	</DL>
97
98	<P>
99	A multi-line statement may be given by specifying each line as a
100	separate statement argument; indented lines are possible by enclosing
101	an argument in quotes and using leading spaces. Multiple
102	<b class="programopt">-s</b> options are treated similarly.
103
104	<P>
105	If <b class="programopt">-n</b> is not given, a suitable number of loops is
106	calculated by trying successive powers of 10 until the total time is
107	at least 0.2 seconds.
108
109	<P>
110	The default timer function is platform dependent. On Windows,
111	<tt class="function">time.clock()</tt> has microsecond granularity but
112	<tt class="function">time.time()</tt>'s granularity is 1/60th of a second; on <span class="Unix">Unix</span>,
113	<tt class="function">time.clock()</tt> has 1/100th of a second granularity and
114	<tt class="function">time.time()</tt> is much more precise. On either platform, the
115	default timer functions measure wall clock time, not the CPU time.
116	This means that other processes running on the same computer may
117	interfere with the timing. The best thing to do when accurate timing
118	is necessary is to repeat the timing a few times and use the best
119	time. The <b class="programopt">-r</b> option is good for this; the default of 3
120	repetitions is probably enough in most cases. On <span class="Unix">Unix</span>, you can use
121	<tt class="function">time.clock()</tt> to measure CPU time.
122
123	<P>
124	<div class="note"><b class="label">Note:</b>
125	There is a certain baseline overhead associated with executing a
126	pass statement. The code here doesn't try to hide it, but you
127	should be aware of it. The baseline overhead can be measured by
128	invoking the program without arguments.
129	</div>
130
131	<P>
132	The baseline overhead differs between Python versions! Also, to
133	fairly compare older Python versions to Python 2.3, you may want to
134	use Python's <b class="programopt">-O</b> option for the older versions to avoid
135	timing <code>SET_LINENO</code> instructions.
136
137	<P>
138
139	<DIV CLASS="navigation">
140	<div class='online-navigation'>
141	<p></p><hr />
142	<table align="center" width="100%" cellpadding="0" cellspacing="2">
143	<tr>
144	<td class='online-navigation'><a rel="prev" title="10.10 timeit "
145	href="module-timeit.html"><img src='../icons/previous.png'
146	border='0' height='32' alt='Previous Page' width='32' /></A></td>
147	<td class='online-navigation'><a rel="parent" title="10.10 timeit "
148	href="module-timeit.html"><img src='../icons/up.png'
149	border='0' height='32' alt='Up One Level' width='32' /></A></td>
150	<td class='online-navigation'><a rel="next" title="10.10.2 Examples"
151	href="node465.html"><img src='../icons/next.png'
152	border='0' height='32' alt='Next Page' width='32' /></A></td>
153	<td align="center" width="100%">Python Library Reference</td>
154	<td class='online-navigation'><a rel="contents" title="Table of Contents"
155	href="contents.html"><img src='../icons/contents.png'
156	border='0' height='32' alt='Contents' width='32' /></A></td>
157	<td class='online-navigation'><a href="modindex.html" title="Module Index"><img src='../icons/modules.png'
158	border='0' height='32' alt='Module Index' width='32' /></a></td>
159	<td class='online-navigation'><a rel="index" title="Index"
160	href="genindex.html"><img src='../icons/index.png'
161	border='0' height='32' alt='Index' width='32' /></A></td>
162	</tr></table>
163	<div class='online-navigation'>
164	<b class="navlabel">Previous:</b>
165	<a class="sectref" rel="prev" href="module-timeit.html">10.10 timeit </A>
166	<b class="navlabel">Up:</b>
167	<a class="sectref" rel="parent" href="module-timeit.html">10.10 timeit </A>
168	<b class="navlabel">Next:</b>
169	<a class="sectref" rel="next" href="node465.html">10.10.2 Examples</A>
170	</div>
171	</div>
172	<hr />
173	<span class="release-info">Release 2.4.2, documentation updated on 28 September 2005.</span>
174	</DIV>
175	<!--End of Navigation Panel-->
176	<ADDRESS>
177	See <i><a href="about.html">About this document...</a></i> for information on suggesting changes.
178	</ADDRESS>
179	</BODY>
180	</HTML>