Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758614Ab2JXMb1 (ORCPT ); Wed, 24 Oct 2012 08:31:27 -0400 Received: from mga03.intel.com ([143.182.124.21]:13788 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758385Ab2JXMbZ (ORCPT ); Wed, 24 Oct 2012 08:31:25 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.80,639,1344236400"; d="scan'208";a="159797026" Date: Wed, 24 Oct 2012 05:31:24 -0700 From: Andi Kleen To: Stephane Eranian Cc: "Yan, Zheng" , LKML , Peter Zijlstra Subject: Re: [PATCH V2 6/7] perf, x86: Use LBR call stack to get user callchain Message-ID: <20121024123124.GU2095@tassilo.jf.intel.com> References: <1351058350-9159-1-git-send-email-zheng.z.yan@intel.com> <1351058350-9159-7-git-send-email-zheng.z.yan@intel.com> <5087CF96.7010406@intel.com> <5087D678.1080905@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 801 Lines: 21 On Wed, Oct 24, 2012 at 02:21:43PM +0200, Stephane Eranian wrote: > But still, if I do: > $ perf record -g -e cpu/cycles/k ........ > > Looks like your code will activate LBR cstack for user stack even > though I don't use it. > I know it won't generate any user samples (theoretically) but you are > still commandeering > the LBR resource which other events may want to use. You can disable it in sysfs. LBR is a power user feature and they will know how to do this. See it as a "prefer the needs of the 95+% over the needs of the few" default -Andi -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/