Function Call Tracing
Purpose
Trace all function calls in C/C++ programs with per-thread logs and Perfetto visualization.
Components
- Instrumentation Library (trace_instrument.c)
Captures function entry/exit, writes per-thread logs.
Build:
gcc -c -fPIC trace_instrument.c -o trace_instrument.o gcc -shared trace_instrument.o -o libtrace.so -ldl -lpthread
- Perfetto Converter (trace_to_perfetto.cpp)
Converts logs to Chrome JSON for Perfetto UI.
Build:
g++ -O3 -std=c++17 trace_to_perfetto.cpp -o trace_to_perfetto
Usage
Step 1: Add to Build
CFLAGS += -finstrument-functions -g LDFLAGS += -L. -ltrace -ldl -lpthread
Step 2: Build Target
make
Step 3: Run
export LD_LIBRARY_PATH=.:$LD_LIBRARY_PATH ./program
Creates trace_<tid>.log files
Step 4: Convert to Perfetto
./trace_to_perfetto trace_*.log -o trace.json
Open trace.json in ui.perfetto.dev
Log Format
[seq] [timestamp] [dots] [ENTRY|EXIT!] function_name [0] [1.000000000] [ENTRY] main [1] [1.000050000] . [ENTRY] helper [2] [1.000100000] . [EXIT!] helper [3] [1.000150000] [EXIT!] main
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Dots indicate call depth
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Timestamp in seconds.nanoseconds
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One log file per thread
When User Requests Tracing
Steps
-
Copy trace_instrument.c and trace_to_perfetto.cpp to project
-
Build instrumentation library
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Add -finstrument-functions to CFLAGS
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Add -L. -ltrace -ldl -lpthread to LDFLAGS
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Build project
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Set LD_LIBRARY_PATH and run
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Convert logs: ./trace_to_perfetto trace_*.log -o trace.json
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Provide link to ui.perfetto.dev
Build System Detection
Makefile: Add flags conditionally
ENABLE_TRACE ?= 0 ifeq ($(ENABLE_TRACE),1) CFLAGS += -finstrument-functions -g LDFLAGS += -L. -ltrace -ldl -lpthread endif
CMake: Add option
option(ENABLE_TRACE "Enable tracing" OFF) if(ENABLE_TRACE) add_compile_options(-finstrument-functions -g) link_libraries(trace dl pthread) endif()
Output
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trace_.log: Per-thread text logs
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trace.json: Perfetto Chrome JSON format
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View at https://ui.perfetto.dev
Perfetto JSON Format
Function ENTRY → "B" (begin) event Function EXIT! → "E" (end) event All threads aligned by timestamp in single file.