How do I enable C++ demangling for the perf callgraph? It seems to demangle symbols when I go into annotate mode, but not in the main callgraph.
Sample code (using Google Benchmark):
#include <benchmark/benchmark.h> #include <vector> static __attribute__ ((noinline)) int my_really_big_function() { for(size_t i = 0; i < 1000; ++i) { benchmark::DoNotOptimize(i % 5); } return 0; } static __attribute__ ((noinline)) void caller1() { for(size_t i = 0; i < 1000; ++i) { benchmark::DoNotOptimize(my_really_big_function()); benchmark::DoNotOptimize(i % 5); } } static __attribute__ ((noinline)) void myfun(benchmark::State& state) { while(state.KeepRunning()) { caller1(); } } BENCHMARK(myfun); BENCHMARK_MAIN();
build command:
clang++ main.cpp -o main -fno-omit-frame-pointer -O0 -lpthread -lbenchmark
perf commands:
perf record -g ./main perf report -g 'graph,0.5,caller'
I’ve also tried enabling the –demangle option, but that doesn’t seem to affect the output.
callgraph missing demangled symbols:
Samples: 3K of event 'cycles', Event count (approx.): 2946754102 Children Self Command Shared Object Symbol + 99.82% 0.00% main main [.] _ZL5myfunRN9benchmark5StateE + 99.82% 0.00% main main [.] _ZN9benchmark12_GLOBAL__N_111RunInThreadEPKNS_8internal9Benchmark8InstanceEmiPNS0_11ThreadStatsE + 99.82% 0.00% main main [.] _ZN9benchmark22RunSpecifiedBenchmarksEPNS_17BenchmarkReporterE + 99.82% 0.00% main main [.] main + 99.82% 0.00% main libc-2.21.so [.] __libc_start_main + 99.82% 0.00% main [unknown] [.] 0x7fbe258d4c544155 + 99.75% 0.30% main main [.] _ZL7caller1v + 99.52% 99.46% main main [.] _ZL22my_really_big_functionv
annotated disassembly showing demangled calls:
│ │ 0000000000404310 <caller1()>: │ _ZL7caller1v(): │ push %rbp │ mov %rsp,%rbp | $0x30,%rsp | $0x0,-0x18(%rbp) │10: cmpq $0x3e8,-0x18(%rbp) │ ↓ jae 6f │ → callq my_really_big_function() │ lea -0x1c(%rbp),%rcx │ mov %eax,-0x1c(%rbp) 14.29 │ mov %rcx,-0x10(%rbp) │ mov -0x10(%rbp),%rcx │ lea -0x28(%rbp),%rcx │ mov $0x5,%eax │ mov %eax,%edx │ mov -0x18(%rbp),%rax │ xor %esi,%esi │ mov %rdx,-0x30(%rbp) │ mov %esi,%edx │ mov -0x30(%rbp),%rdi │ div %rdi 85.71 │ mov %rdx,-0x28(%rbp) │ mov %rcx,-0x8(%rbp) │ mov -0x8(%rbp),%rcx │ mov -0x18(%rbp),%rax │ add $0x1,%rax │ mov %rax,-0x18(%rbp) │ ↑ jmpq 10 │6f: add $0x30,%rsp │ pop %rbp │ ← retq
System info:
- Ubuntu 15.04 64-bit
- Intel i5-6600k
- perf 3.19.8-ckt6
- clang 3.6.0-2ubuntu1
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Answer
I had the same problem on the Ubuntu 15.10 and I found the solution here: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1396654
Update: works also for Ubuntu 18.10
Here are the steps:
sudo apt-get install libiberty-dev binutils-dev mkdir ~/install cd ~/install # If the following apt-get doesn't work on your system, # uncomment deb-src lines in your /etc/apt/sources.list, # as suggested by @ctitze # or you can download it manually from packages.ubuntu.com # as @aleixrocks suggested in the comment below apt-get source linux-tools-`uname -r` sudo apt-get build-dep linux-tools-`uname -r` cd linux-`uname -r | sed 's/-.*//'`/tools/perf make # now you should see the new "perf" executable here ./perf
There should be also some way to create a new linux-tools-common package to really integrate it into your system. For now to override the official perf with your new one, just set your PATH:
export PATH=~/install/linux-`uname -r | sed 's/-.*//'`/tools/perf:$PATH