From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753840AbbAUUIA (ORCPT ); Wed, 21 Jan 2015 15:08:00 -0500 Received: from foss-mx-na.foss.arm.com ([217.140.108.86]:40516 "EHLO foss-mx-na.foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752110AbbAUUHx (ORCPT ); Wed, 21 Jan 2015 15:07:53 -0500 Message-ID: <1421870862.14076.107.camel@arm.com> Subject: Re: [PATCH v4 1/3] perf: Use monotonic clock as a source for timestamps From: Pawel Moll To: Peter Zijlstra Cc: Richard Cochran , Steven Rostedt , Ingo Molnar , Paul Mackerras , Arnaldo Carvalho de Melo , John Stultz , Masami Hiramatsu , Christopher Covington , Namhyung Kim , David Ahern , Thomas Gleixner , Tomeu Vizoso , "linux-kernel@vger.kernel.org" , "linux-api@vger.kernel.org" Date: Wed, 21 Jan 2015 20:07:42 +0000 In-Reply-To: <1421869684.14076.105.camel@arm.com> References: <1415292718-19785-1-git-send-email-pawel.moll@arm.com> <1415292718-19785-2-git-send-email-pawel.moll@arm.com> <20150105130035.GP30905@twins.programming.kicks-ass.net> <1421855543.14076.68.camel@arm.com> <1421869684.14076.105.camel@arm.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.12.10-0ubuntu1~14.10.1 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2015-01-21 at 19:48 +0000, Pawel Moll wrote: > On Wed, 2015-01-21 at 15:52 +0000, Pawel Moll wrote: > > On Mon, 2015-01-05 at 13:00 +0000, Peter Zijlstra wrote: > > > On Thu, Nov 06, 2014 at 04:51:56PM +0000, Pawel Moll wrote: > > > > Documentation/kernel-parameters.txt | 9 +++++++++ > > > > kernel/events/core.c | 37 +++++++++++++++++++++++++++++++++++++ > > > > 2 files changed, 46 insertions(+) > > > > > > > diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt > > > > index 4c81a86..8ead8d8 100644 > > > > --- a/Documentation/kernel-parameters.txt > > > > +++ b/Documentation/kernel-parameters.txt > > > > > > > @@ -2763,6 +2764,14 @@ bytes respectively. Such letter suffixes can also be entirely omitted. > > > > allocator. This parameter is primarily for debugging > > > > and performance comparison. > > > > > > > > + perf_use_local_clock > > > > + [PERF] > > > > + Use local_clock() as a source for perf timestamps > > > > + generation. This was be the default behaviour and > > > > + this parameter can be used to maintain backward > > > > + compatibility or on older hardware with expensive > > > > + monotonic clock source. > > > > + > > > > pf. [PARIDE] > > > > See Documentation/blockdev/paride.txt. > > > > > > So I'm always terminally confused on the naming of kernel parameters, > > > sometimes things are modules (even when they're not actually =m capable) > > > and get a module::foo naming or so and sometimes they're not. > > > > I guess you mean module.foo? > > > > > So we want to use the module naming thing or not? > > > > Honestly, I don't mind either way. For one thing ftrace doesn't bother > > and just uses __setup() as well. > > There's one more thing to this - as far as I remember, the module name > is actually derived from the compilation unit name (at some level of > Kbuild). I may be wrong (will have to double check), but a module > parameter defined in kernel/events/core.c may be called something like > "core.parameter" ;-). Ok, so it's possible to enforce "perf." prefix: /* You can override this manually, but generally this should match the module name. */ #ifdef MODULE #define MODULE_PARAM_PREFIX /* empty */ #else #define MODULE_PARAM_PREFIX KBUILD_MODNAME "." #endif So, perf_use_local_clock or perf.use_local_clock? :-) Pawel