perf can find symbol in the kernel ,but can not find symbol in my program. How to fix it?
linux, perf, performance
Solution
Today, when I run `perf test`, I got a message saying `vmlinux symtab matches kallsyms: Failed`.
When I was looking for the reason, I found that the reason is that the value of `/proc/sys/kernel/kptr_restrict` is 1. When we set it to `0`, we will get the symbol in our program.
Problem
you may have read this question: how can i get perf to find symbols in my program 1)my question is: when I use perf report , it gives a result like this: ``` # Overhead Command Shared Object Symbol # . . # 99.59% test test [.] 0x000003d4 0.21% test [kernel.kallsyms] [k] __do_fault 0.10% test [kernel.kallsyms] [k] run_timer_softirq 0.10% test [kernel.kallsyms] [k] __update_cpu_load 0.01% test [kernel.kallsyms] [k] set_task_comm 0.00% test [kernel.kallsyms] [k] intel_pmu_enable_all ``` That is: the perf can find symbol in kernel but cannot find symbol in my program. my program is here: ``` void longa() { int i,j; for(i = 0; i < 1000000; i++) j=i; //am I silly or crazy? I feel boring and desperate. } void foo2() { int i; for(i=0 ; i < 10; i++) longa(); } void foo1() { int i; for(i = 0; i< 100; i++) longa(); } int main(void) { foo1(); foo2(); } ``` 2)I have compile the program like: gcc test.c -g -o test My env: os:ubuntu kernel:3.10.9