Process Profiling

1. Perf + FlameGraph

Process의 FlameGraph를 뽑아내는 과정을 설명한다. Perf의 --call-graph 기능을 이용한다.

1) Kernel setting

echo -1 > /proc/sys/kernel/perf_event_paranoid
echo 0 > /proc/sys/kernel/kptr_restrict
chmod a+r /proc/kallsyms
echo 100 > /proc/sys/kernel/perf_cpu_time_max_percent
echo performance > /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor

2) Get perf data

perf record -o perf.data --call-graph=dwarf -F 15000 -p {PID}
perf script --max-stack 1024 --input=perf.data -f > out.perf

3) Create FlameGraph

c++filt < out.perf > out.perf_filted
stackcollapse-perf.pl --all out.perf_filted > out.perf_collapsed
flamegraph.pl -color=java --hash out.perf_collapsed > FlameGraph.svg

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2. Count function call using gdb

1) Create breakpoint

 break func_name
 ...
 • [23] break number

2) Ignore break point

ignore 23 1000000   # set ignore count very high.

3) Run or Continue

run  # the program will SIGSEGV before reaching the ignore count.
     # Once it stops with SIGSEGV:

4) Show count

info break 23  # tells you how many times the breakpoint has been hit, 
               # which is exactly the count you want