Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753286Ab2HCJ1u (ORCPT ); Fri, 3 Aug 2012 05:27:50 -0400 Received: from hqemgate04.nvidia.com ([216.228.121.35]:5143 "EHLO hqemgate04.nvidia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753164Ab2HCJ1t convert rfc822-to-8bit (ORCPT ); Fri, 3 Aug 2012 05:27:49 -0400 X-PGP-Universal: processed; by hqnvupgp06.nvidia.com on Fri, 03 Aug 2012 02:27:47 -0700 From: Venu Byravarasu To: Vikram Pandita , "gregkh@linuxfoundation.org" , "kay@vrfy.org" CC: "linux-kernel@vger.kernel.org" , Mike Turquette , Vimarsh Zutshi Date: Fri, 3 Aug 2012 14:57:42 +0530 Subject: RE: [PATCH v2] printk: add option to print cpu id Thread-Topic: [PATCH v2] printk: add option to print cpu id Thread-Index: Ac1xWMtvTs8UoHTwQBiUNqGfW2tFVwAALGNQ Message-ID: References: <1343985378-22330-1-git-send-email-vikram.pandita@ti.com> In-Reply-To: <1343985378-22330-1-git-send-email-vikram.pandita@ti.com> Accept-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: acceptlanguage: en-US MIME-Version: 1.0 Content-Language: en-US Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1961 Lines: 44 > -----Original Message----- > From: linux-kernel-owner@vger.kernel.org [mailto:linux-kernel- > owner@vger.kernel.org] On Behalf Of Vikram Pandita > Sent: Friday, August 03, 2012 2:46 PM > To: gregkh@linuxfoundation.org; kay@vrfy.org > Cc: linux-kernel@vger.kernel.org; Vikram Pandita; Mike Turquette; Vimarsh > Zutshi > Subject: [PATCH v2] printk: add option to print cpu id > > From: Vikram Pandita > > Introduce config option to enable CPU id reporting for printk() calls. > > Example logs with this option enabled look like: > [1] [ 2.328613] usbcore: registered new interface driver libusual > [1] [ 2.335418] usbcore: registered new interface driver usbtest > [1] [ 2.342803] mousedev: PS/2 mouse device common for all mice > [0] [ 2.352600] twl_rtc twl_rtc: Power up reset detected. > [0] [ 2.359191] twl_rtc twl_rtc: Enabling TWL-RTC > [1] [ 2.367797] twl_rtc twl_rtc: rtc core: registered twl_rtc as rtc0 > [1] [ 2.375274] i2c /dev entries driver > [1] [ 2.382324] Driver for 1-wire Dallas network protocol. > > Its sometimes very useful to have printk also print the CPU Identifier > that executed the call. This has helped to debug various SMP issues on > shipping > products. Is it not better to have macros which will have wrapper to printk with required debug info added? E.g. cpu# in your case. If by default we add cupid, is it not over head in each message getting printed with printk? > > Known limitation is if the system gets preempted between function call and > actual printk, the reported cpu-id might not be accurate. But most of the > times its seen to give a good feel of how the N cpu's in the system are > getting loaded. > -- 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/