From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Ahern Subject: Re: perf record always record the same kernel symbol Date: Fri, 10 May 2013 14:22:42 -0600 Message-ID: <518D5712.5070907@gmail.com> References: <518D46AA.1000006@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from mail-da0-f43.google.com ([209.85.210.43]:44172 "EHLO mail-da0-f43.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754397Ab3EJUWs (ORCPT ); Fri, 10 May 2013 16:22:48 -0400 Received: by mail-da0-f43.google.com with SMTP id u7so533499dae.16 for ; Fri, 10 May 2013 13:22:47 -0700 (PDT) In-Reply-To: Sender: linux-perf-users-owner@vger.kernel.org List-ID: To: Chao Xu Cc: linux-perf-users@vger.kernel.org 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