From mboxrd@z Thu Jan 1 00:00:00 1970 From: Arun Sharma Subject: Using a new perf tool against an older kernel Date: Wed, 22 Jun 2011 14:39:47 -0700 Message-ID: <4E026123.4060208@fb.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from outmail018.snc4.facebook.com ([66.220.144.150]:40647 "EHLO mx-out.facebook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S932248Ab1FVVi4 (ORCPT ); Wed, 22 Jun 2011 17:38:56 -0400 Sender: linux-perf-users-owner@vger.kernel.org List-ID: To: linux-perf-users@vger.kernel.org Cc: linux-kernel@vger.kernel.org I ran into a few strange issues today using a new perf tool (3.0-rcX) against a 2.6.38 based kernel. Basic things seem to work: # perf record -aR -- sleep 1 [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 0.443 MB perf.data (~19334 samples) ] But: # perf record -agR -- sleep 1 [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 1.558 MB perf.data (~68077 samples) ] Can't find id 9's machine Found 1 unknown events! Is this an older tool processing a perf.data file generated by a more recent tool? If that is not the case, consider reporting to linux-kernel@vger.kernel.org. I couldn't tell if this is kernel/user space incompatibility or tighter error checking in the new perf tool. Before I start digging further, thought I'd ask if this combination is supported. The error message above doesn't ask me: Are you using an old kernel? -Arun