Re: perf record always record the same kernel symbol

[David Ahern <dsahern@gmail.com>]

On 5/10/13 1:58 PM, Chao Xu wrote:
> Thanks David. This indeed gave more samples. Do you know why the symbol
>   [k] 0xffffffff81043fea occured so often? As shown in the pasted
> result, both "swapper" and "perf" had this symbol. And if I "perf record
> dd if=/dev/zero of=/dev/null" or "perf record ping", they all showed
> this symbol. I pasted these results in the end of this email.
> I guess my real concern is the symbols cannot be mapped into meaningful
> function names. These symbols cannot be found in either /proc/kallsyms
> nor the vmlinux I built from the kernel source tree. Any idea? Thanks.

take a look at the output of report -v and report -D. For me those 
commands work just fine:

# perf record -a -- sleep 1
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.104 MB perf.data (~4527 samples) ]

# perf report

  38.39%       swapper  [kernel.kallsyms]   [k] intel_idle
   9.26%          perf  [kernel.kallsyms]   [k] generic_exec_single
   5.58%       swapper  [kernel.kallsyms]   [k] cpuidle_wrap_enter
   4.73%       swapper  [kernel.kallsyms]   [k] hpet_legacy_next_event
   4.47%       swapper  [kernel.kallsyms]   [k] _raw_spin_lock_irqsave
...

David