Difference between revisions of "Gprof Tutorial"
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{ | { | ||
|type="()"} | |type="()"} | ||
| − | + | + | + by instrumenting the application during compilation |
|| True | || True | ||
| − | - | + | - through static analysis of the source code |
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| − | - | + | - by means of hardware performance counters |
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</quiz> | </quiz> | ||
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{{hidden begin | {{hidden begin | ||
| − | |title = 3. What compiler flag is used to instrument the application? | + | |title = 3. What compiler/linker flag is used to instrument the application? |
}} | }} | ||
<quiz display=simple> | <quiz display=simple> | ||
{ | { | ||
|type="()"} | |type="()"} | ||
| − | + | + | + <code>-pg</code> |
|| True | || True | ||
| − | - | + | - <code>-pig</code> |
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| − | - | + | - <code>--profile</code> |
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</quiz> | </quiz> | ||
| Line 60: | Line 60: | ||
{{hidden begin | {{hidden begin | ||
| − | |title = 4. Which | + | |title = 4. Which compilers support Gprof? |
}} | }} | ||
<quiz display=simple> | <quiz display=simple> | ||
{ | { | ||
|type="()"} | |type="()"} | ||
| − | - only commercial compilers | + | - only the commercial Intel compilers |
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- only open-source compilers (e.g., from GNU) | - only open-source compilers (e.g., from GNU) | ||
| Line 75: | Line 75: | ||
{{hidden begin | {{hidden begin | ||
| − | |title = | + | |title = 5. How should the input parameters be when running the instrumented application? |
}} | }} | ||
<quiz display=simple> | <quiz display=simple> | ||
{ | { | ||
|type="()"} | |type="()"} | ||
| − | - | + | - simple and understandable |
|| | || | ||
| − | + | + | + representative of a usual workload |
|| True | || True | ||
| − | - | + | - covering edge cases |
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</quiz> | </quiz> | ||
| Line 90: | Line 90: | ||
{{hidden begin | {{hidden begin | ||
| − | |title = | + | |title = 6. Which applications can be analyzed with Gprof? |
}} | }} | ||
<quiz display=simple> | <quiz display=simple> | ||
{ | { | ||
|type="()"} | |type="()"} | ||
| − | - | + | - only small examples |
| + | || | ||
| + | - up to medium-sized applications with a running time below ~1 hour | ||
| + | || | ||
| + | + all, even large real-world examples with huge running times | ||
| + | || True | ||
| + | </quiz> | ||
| + | {{hidden end}} | ||
| + | |||
| + | {{hidden begin | ||
| + | |title = 7. What is a call graph? | ||
| + | }} | ||
| + | <quiz display=simple> | ||
| + | { | ||
| + | |type="()"} | ||
| + | - an android app to show incoming callers | ||
|| | || | ||
| − | + | + | + a hierarchy diagram of function calls in a given profile |
|| True | || True | ||
| − | - | + | - instructions of how to call for help during emergencies |
|| | || | ||
</quiz> | </quiz> | ||
| Line 105: | Line 120: | ||
{{hidden begin | {{hidden begin | ||
| − | |title = | + | |title = 8. How do you generate a call graph of a Gprof profile? |
}} | }} | ||
<quiz display=simple> | <quiz display=simple> | ||
| Line 120: | Line 135: | ||
{{hidden begin | {{hidden begin | ||
| − | |title = | + | |title = 9. What is gprof2dot? |
}} | }} | ||
<quiz display=simple> | <quiz display=simple> | ||
{ | { | ||
|type="()"} | |type="()"} | ||
| − | + | + | + third-party script for call graph visualization via the "dot" library |
|| True | || True | ||
- Gprof feature to export profiles as a pdf | - Gprof feature to export profiles as a pdf | ||
|| | || | ||
| − | - | + | - a fork of the beta version of Gprof2 |
|| | || | ||
</quiz> | </quiz> | ||
| Line 135: | Line 150: | ||
{{hidden begin | {{hidden begin | ||
| − | |title = | + | |title = 10. Does Gprof work with parallel applications? |
}} | }} | ||
<quiz display=simple> | <quiz display=simple> | ||
{ | { | ||
|type="()"} | |type="()"} | ||
| − | - | + | - no, Gprof only works with sequential applications |
|| | || | ||
| − | + | + | + yes, but Gprof cannot differentiate between individual threads or processes |
|| True | || True | ||
| − | - | + | - yes, parallel profiling is the main use-case of Gprof |
|| | || | ||
</quiz> | </quiz> | ||
| Line 150: | Line 165: | ||
{{hidden begin | {{hidden begin | ||
| − | |title = | + | |title = 11. How much runtime overhead does Gprof produce? |
}} | }} | ||
<quiz display=simple> | <quiz display=simple> | ||
{ | { | ||
|type="()"} | |type="()"} | ||
| − | - | + | - none |
|| | || | ||
| − | + | + | + little |
|| True | || True | ||
| − | - | + | - much |
|| | || | ||
</quiz> | </quiz> | ||
{{hidden end}} | {{hidden end}} | ||
Latest revision as of 18:48, 3 December 2020
This tutorial deals with the topic of applications performance analysis with the GNU profiler Gprof. Profiling applications gives valuable insights into the program structure and exposes performance bottlenecks, which point to sections of the code where optimizations are most effective.
The tutorial covers all necessary basics to get started with Gprof: it shows how to instrument applications, how to generate performance information for an application run and how to evaluate the results. In addition, it explains how to visualize the application structure using call graphs and how to annotate the application's source code with runtime information. Three real-world examples from the areas of biology, computer science and mechanical engineering demonstrate that this works with different programming languages (C/C++, Fortran), different compilers (GNU, Intel) and even parallel applications (threads, MPI).
Quiz
1. What languages can Gprof profile?
2. How does Gprof generate a performance profile of an application?
3. What compiler/linker flag is used to instrument the application?
4. Which compilers support Gprof?
5. How should the input parameters be when running the instrumented application?
6. Which applications can be analyzed with Gprof?
7. What is a call graph?
8. How do you generate a call graph of a Gprof profile?
9. What is gprof2dot?
10. Does Gprof work with parallel applications?
11. How much runtime overhead does Gprof produce?