From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754396AbcGTOg7 (ORCPT ); Wed, 20 Jul 2016 10:36:59 -0400 Received: from mail-wm0-f42.google.com ([74.125.82.42]:38611 "EHLO mail-wm0-f42.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754035AbcGTOgv (ORCPT ); Wed, 20 Jul 2016 10:36:51 -0400 Subject: Re: Strange behavior of perf top with PEBS To: Jiri Olsa References: <578F7C82.6090500@kyup.com> <20160720143417.GA25992@krava> Cc: Peter Zijlstra , "Linux-Kernel@Vger. Kernel. Org" , andi@firstfloor.org From: Nikolay Borisov Message-ID: <578F8C7E.9080503@kyup.com> Date: Wed, 20 Jul 2016 17:36:46 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.1.0 MIME-Version: 1.0 In-Reply-To: <20160720143417.GA25992@krava> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 07/20/2016 05:34 PM, Jiri Olsa wrote: > On Wed, Jul 20, 2016 at 04:28:34PM +0300, Nikolay Borisov wrote: >> Hello, >> >> Running perf version 4.4.14.g0cb188d (no modification to the PMU/perf >> code) I observed that "perf top" counts no cycles and produces no >> output. After a bit of head scratching and testing I figured that >> running "perf top -e cycles" actually works whereas the default option >> is equivalent to running "perf top -e cycles:p". So the latter version >> seems to not work on my machine. > > hum, I think Core2 has PEBs valid only for instructions not cycles.. FYI running perf top -e instructions:p also produces no data on that particular CPU. > > I'll check why perf top forcing the precise for cycles > I thought we had that automated already > > jirka >