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<!-- Copyright (C) 2003 Red Hat, Inc.                                -->
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<HTML
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>Profiling functions</TITLE
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><DIV
CLASS="CHAPTER"
><H1
><A
NAME="PROFILE-FUNCTIONS">Chapter 52. Profiling functions</H1
><DIV
CLASS="SECT1"
><H1
CLASS="SECT1"
><A
NAME="SERVICES-PROFILE-API">API</H1
><P
>In order for profile data to be gathered for an application, the
program has to initiate the process.
Once started, execution histogram data will be collected in a
dynamic memory buffer.
This data can be uploaded to a host using <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>TFTP</I
></SPAN
>.
A side effect of the upload of the data is that the histogram
is reset.
This is useful, especially for high resolution histograms, since
the histogram data are collected as 16-bit counters which can be quickly
saturated.
For example, if the histogram is being collected at a rate of 10,000
samples per second, a hot spot in the program could saturate after
only 6.5 seconds.</P
><P
> The API for the application profiling functions can be
found in the file <TT
CLASS="FILENAME"
>&lt;cyg/profile/profile.h&gt;</TT
>.</P
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="SERVICES-PROFILE-API-PROFILE-ON">profile_on</H2
><P
>This function is used to initiate the gathering of the
runtime execution histogram data.</P
><TABLE
BORDER="5"
BGCOLOR="#E0E0F0"
WIDTH="70%"
><TR
><TD
><PRE
CLASS="PROGRAMLISTING"
>void profile_on(void *start, void *end, int bucket_size, int resolution);</PRE
></TD
></TR
></TABLE
><P
>Calling this function will initiate execution profiling.
An execution histogram is collected at the rate of
<TT
CLASS="PARAMETER"
><I
>resolution</I
></TT
> times per second.
The area between <TT
CLASS="PARAMETER"
><I
>start</I
></TT
> and <TT
CLASS="PARAMETER"
><I
>end</I
></TT
>
will be divided up into a number of buckets, each representing
<TT
CLASS="PARAMETER"
><I
>bucket_size</I
></TT
>
program bytes in length.  Using statistical sampling (via a high speed timer), when
the program counter is found to be within the range
<TT
CLASS="PARAMETER"
><I
>start</I
></TT
>..<TT
CLASS="PARAMETER"
><I
>end</I
></TT
>, the appropriate
bucket (histogram entry) will be incremented.</P
><P
>The choice of <TT
CLASS="PARAMETER"
><I
>resolution</I
></TT
> and <TT
CLASS="PARAMETER"
><I
>bucket_size</I
></TT
>
control how large the data gathered will be, as well as how much overhead is
encumbered for gathering the histogram.
Smaller values for <TT
CLASS="PARAMETER"
><I
>bucket_size</I
></TT
> will garner better
results (<TT
CLASS="FUNCTION"
>gprof</TT
> can more closely align the data with
actual function names) at the expense of a larger data buffer.</P
><DIV
CLASS="NOTE"
><BLOCKQUOTE
CLASS="NOTE"
><P
><B
>NOTE: </B
>The value of <TT
CLASS="PARAMETER"
><I
>bucket_size</I
></TT
> will be rounded up to a power of two.</P
></BLOCKQUOTE
></DIV
></DIV
></DIV
></DIV
><DIV
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><HR
ALIGN="LEFT"
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><A
HREF="services-profile-gprof.html"
ACCESSKEY="P"
>Prev</A
></TD
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HREF="ecos-ref.html"
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>Home</A
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><TR
><TD
WIDTH="33%"
ALIGN="left"
VALIGN="top"
>Application profiling</TD
><TD
WIDTH="34%"
ALIGN="center"
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><A
HREF="services-profile-gprof.html"
ACCESSKEY="U"
>Up</A
></TD
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ALIGN="right"
VALIGN="top"
>eCos Power Management Support</TD
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></HTML
>

Line No.	Rev	Author	Line
1	28	unneback	`<!-- Copyright (C) 2003 Red Hat, Inc. -->`
2			`<!-- This material may be distributed only subject to the terms -->`
3			`<!-- and conditions set forth in the Open Publication License, v1.0 -->`
4			`<!-- or later (the latest version is presently available at -->`
5			`<!-- http://www.opencontent.org/openpub/). -->`
6			`<!-- Distribution of the work or derivative of the work in any -->`
7			`<!-- standard (paper) book form is prohibited unless prior -->`
8			`<!-- permission is obtained from the copyright holder. -->`
9			`<HTML`
10			`><HEAD`
11			`><TITLE`
12			`>Profiling functions</TITLE`
13			`><meta name="MSSmartTagsPreventParsing" content="TRUE">`
14			`<META`
15			`NAME="GENERATOR"`
16			`CONTENT="Modular DocBook HTML Stylesheet Version 1.76b+`
17			`"><LINK`
18			`REL="HOME"`
19			`TITLE="eCos Reference Manual"`
20			`HREF="ecos-ref.html"><LINK`
21			`REL="UP"`
22			`TITLE="Application profiling"`
23			`HREF="services-profile-gprof.html"><LINK`
24			`REL="PREVIOUS"`
25			`TITLE="Application profiling"`
26			`HREF="services-profile-gprof.html"><LINK`
27			`REL="NEXT"`
28			`TITLE="eCos Power Management Support"`
29			`HREF="services-power.html"></HEAD`
30			`><BODY`
31			`CLASS="CHAPTER"`
32			`BGCOLOR="#FFFFFF"`
33			`TEXT="#000000"`
34			`LINK="#0000FF"`
35			`VLINK="#840084"`
36			`ALINK="#0000FF"`
37			`><DIV`
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40			`SUMMARY="Header navigation table"`
41			`WIDTH="100%"`
42			`BORDER="0"`
43			`CELLPADDING="0"`
44			`CELLSPACING="0"`
45			`><TR`
46			`><TH`
47			`COLSPAN="3"`
48			`ALIGN="center"`
49			`>eCos Reference Manual</TH`
50			`></TR`
51			`><TR`
52			`><TD`
53			`WIDTH="10%"`
54			`ALIGN="left"`
55			`VALIGN="bottom"`
56			`><A`
57			`HREF="services-profile-gprof.html"`
58			`ACCESSKEY="P"`
59			`>Prev</A`
60			`></TD`
61			`><TD`
62			`WIDTH="80%"`
63			`ALIGN="center"`
64			`VALIGN="bottom"`
65			`></TD`
66			`><TD`
67			`WIDTH="10%"`
68			`ALIGN="right"`
69			`VALIGN="bottom"`
70			`><A`
71			`HREF="services-power.html"`
72			`ACCESSKEY="N"`
73			`>Next</A`
74			`></TD`
75			`></TR`
76			`></TABLE`
77			`><HR`
78			`ALIGN="LEFT"`
79			`WIDTH="100%"></DIV`
80			`><DIV`
81			`CLASS="CHAPTER"`
82			`><H1`
83			`><A`
84			`NAME="PROFILE-FUNCTIONS">Chapter 52. Profiling functions</H1`
85			`><DIV`
86			`CLASS="SECT1"`
87			`><H1`
88			`CLASS="SECT1"`
89			`><A`
90			`NAME="SERVICES-PROFILE-API">API</H1`
91			`><P`
92			`>In order for profile data to be gathered for an application, the`
93			`program has to initiate the process.`
94			`Once started, execution histogram data will be collected in a`
95			`dynamic memory buffer.`
96			`This data can be uploaded to a host using <SPAN`
97			`CLASS="emphasis"`
98			`><I`
99			`CLASS="EMPHASIS"`
100			`>TFTP</I`
101			`></SPAN`
102			`>.`
103			`A side effect of the upload of the data is that the histogram`
104			`is reset.`
105			`This is useful, especially for high resolution histograms, since`
106			`the histogram data are collected as 16-bit counters which can be quickly`
107			`saturated.`
108			`For example, if the histogram is being collected at a rate of 10,000`
109			`samples per second, a hot spot in the program could saturate after`
110			`only 6.5 seconds.</P`
111			`><P`
112			`> The API for the application profiling functions can be`
113			`found in the file <TT`
114			`CLASS="FILENAME"`
115			`><cyg/profile/profile.h></TT`
116			`>.</P`
117			`><DIV`
118			`CLASS="SECT2"`
119			`><H2`
120			`CLASS="SECT2"`
121			`><A`
122			`NAME="SERVICES-PROFILE-API-PROFILE-ON">profile_on</H2`
123			`><P`
124			`>This function is used to initiate the gathering of the`
125			`runtime execution histogram data.</P`
126			`><TABLE`
127			`BORDER="5"`
128			`BGCOLOR="#E0E0F0"`
129			`WIDTH="70%"`
130			`><TR`
131			`><TD`
132			`><PRE`
133			`CLASS="PROGRAMLISTING"`
134			`>void profile_on(void start, void end, int bucket_size, int resolution);</PRE`
135			`></TD`
136			`></TR`
137			`></TABLE`
138			`><P`
139			`>Calling this function will initiate execution profiling.`
140			`An execution histogram is collected at the rate of`
141			`<TT`
142			`CLASS="PARAMETER"`
143			`><I`
144			`>resolution</I`
145			`></TT`
146			`> times per second.`
147			`The area between <TT`
148			`CLASS="PARAMETER"`
149			`><I`
150			`>start</I`
151			`></TT`
152			`> and <TT`
153			`CLASS="PARAMETER"`
154			`><I`
155			`>end</I`
156			`></TT`
157			`>`
158			`will be divided up into a number of buckets, each representing`
159			`<TT`
160			`CLASS="PARAMETER"`
161			`><I`
162			`>bucket_size</I`
163			`></TT`
164			`>`
165			`program bytes in length. Using statistical sampling (via a high speed timer), when`
166			`the program counter is found to be within the range`
167			`<TT`
168			`CLASS="PARAMETER"`
169			`><I`
170			`>start</I`
171			`></TT`
172			`>..<TT`
173			`CLASS="PARAMETER"`
174			`><I`
175			`>end</I`
176			`></TT`
177			`>, the appropriate`
178			`bucket (histogram entry) will be incremented.</P`
179			`><P`
180			`>The choice of <TT`
181			`CLASS="PARAMETER"`
182			`><I`
183			`>resolution</I`
184			`></TT`
185			`> and <TT`
186			`CLASS="PARAMETER"`
187			`><I`
188			`>bucket_size</I`
189			`></TT`
190			`>`
191			`control how large the data gathered will be, as well as how much overhead is`
192			`encumbered for gathering the histogram.`
193			`Smaller values for <TT`
194			`CLASS="PARAMETER"`
195			`><I`
196			`>bucket_size</I`
197			`></TT`
198			`> will garner better`
199			`results (<TT`
200			`CLASS="FUNCTION"`
201			`>gprof</TT`
202			`> can more closely align the data with`
203			`actual function names) at the expense of a larger data buffer.</P`
204			`><DIV`
205			`CLASS="NOTE"`
206			`><BLOCKQUOTE`
207			`CLASS="NOTE"`
208			`><P`
209			`><B`
210			`>NOTE: </B`
211			`>The value of <TT`
212			`CLASS="PARAMETER"`
213			`><I`
214			`>bucket_size</I`
215			`></TT`
216			`> will be rounded up to a power of two.</P`
217			`></BLOCKQUOTE`
218			`></DIV`
219			`></DIV`
220			`></DIV`
221			`></DIV`
222			`><DIV`
223			`CLASS="NAVFOOTER"`
224			`><HR`
225			`ALIGN="LEFT"`
226			`WIDTH="100%"><TABLE`
227			`SUMMARY="Footer navigation table"`
228			`WIDTH="100%"`
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230			`CELLPADDING="0"`
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232			`><TR`
233			`><TD`
234			`WIDTH="33%"`
235			`ALIGN="left"`
236			`VALIGN="top"`
237			`><A`
238			`HREF="services-profile-gprof.html"`
239			`ACCESSKEY="P"`
240			`>Prev</A`
241			`></TD`
242			`><TD`
243			`WIDTH="34%"`
244			`ALIGN="center"`
245			`VALIGN="top"`
246			`><A`
247			`HREF="ecos-ref.html"`
248			`ACCESSKEY="H"`
249			`>Home</A`
250			`></TD`
251			`><TD`
252			`WIDTH="33%"`
253			`ALIGN="right"`
254			`VALIGN="top"`
255			`><A`
256			`HREF="services-power.html"`
257			`ACCESSKEY="N"`
258			`>Next</A`
259			`></TD`
260			`></TR`
261			`><TR`
262			`><TD`
263			`WIDTH="33%"`
264			`ALIGN="left"`
265			`VALIGN="top"`
266			`>Application profiling</TD`
267			`><TD`
268			`WIDTH="34%"`
269			`ALIGN="center"`
270			`VALIGN="top"`
271			`><A`
272			`HREF="services-profile-gprof.html"`
273			`ACCESSKEY="U"`
274			`>Up</A`
275			`></TD`
276			`><TD`
277			`WIDTH="33%"`
278			`ALIGN="right"`
279			`VALIGN="top"`
280			`>eCos Power Management Support</TD`
281			`></TR`
282			`></TABLE`
283			`></DIV`
284			`></BODY`
285			`></HTML`
286			`>`

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[/] [openrisc/] [trunk/] [rtos/] [ecos-2.0/] [doc/] [html/] [ref/] [profile-functions.html] - Blame information for rev 367