Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756873AbaKTMhj (ORCPT ); Thu, 20 Nov 2014 07:37:39 -0500 Received: from mail-oi0-f43.google.com ([209.85.218.43]:53952 "EHLO mail-oi0-f43.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756136AbaKTMhe (ORCPT ); Thu, 20 Nov 2014 07:37:34 -0500 MIME-Version: 1.0 In-Reply-To: <871toypelb.fsf@sejong.aot.lge.com> References: <1416346617-3577-1-git-send-email-kan.liang@intel.com> <1416346617-3577-2-git-send-email-kan.liang@intel.com> <87r3wzpt4o.fsf@sejong.aot.lge.com> <37D7C6CF3E00A74B8858931C1DB2F07701671D25@SHSMSX103.ccr.corp.intel.com> <871toypelb.fsf@sejong.aot.lge.com> Date: Thu, 20 Nov 2014 13:37:34 +0100 Message-ID: Subject: Re: [PATCH V4 1/3] perf tools: enable LBR call stack support From: Stephane Eranian To: Namhyung Kim Cc: "Liang, Kan" , "acme@kernel.org" , "jolsa@redhat.com" , "a.p.zijlstra@chello.nl" , "linux-kernel@vger.kernel.org" , "mingo@redhat.com" , "paulus@samba.org" , "ak@linux.intel.com" Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Nov 20, 2014 at 7:32 AM, Namhyung Kim wrote: > > On Wed, 19 Nov 2014 14:32:08 +0000, Kan Liang wrote: > >> On Tue, 18 Nov 2014 16:36:55 -0500, kan liang wrote: > >> > + if (attr->exclude_user) { > >> > + attr->exclude_user = 0; > >> > + > >> > + pr_warning("LBR callstack option is only available" > >> > + " to get user callchain information." > >> > + " Force exclude_user to 0.\n"); > >> > + } > >> > >> I'm not sure what's in a higher priority - maybe I missed earlier discussion. > >> IOW what about this? > >> > >> if (attr->exclude_user) { > >> pr_warning("LBR callstack option is only available" > >> " to get user callchain information.\n"); > > > > I think either is fine. I'd like to add more info "Falling back to framepointers." > > based on your changes. > > So the user know what they will get then. > > > > What do you think? > > Looks good to me. But I still slightly prefer not to override user > settings. But it's not a strong opinion though - I'd like to here from > others. > I don't like when the tool changes the use settings under the hood. I think perf did that with cycles -> TASK_CLOCK if PMU was not supported and that was very confusing to me especially with no warning. So if LBR Call stack mode is not avail, then inform the user with a warning or error, don't swap silently. -- 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/