Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752658Ab2HCJst (ORCPT ); Fri, 3 Aug 2012 05:48:49 -0400 Received: from mail-yw0-f46.google.com ([209.85.213.46]:44328 "EHLO mail-yw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752267Ab2HCJss (ORCPT ); Fri, 3 Aug 2012 05:48:48 -0400 MIME-Version: 1.0 In-Reply-To: References: <1343985378-22330-1-git-send-email-vikram.pandita@ti.com> From: Kay Sievers Date: Fri, 3 Aug 2012 11:48:26 +0200 Message-ID: Subject: Re: [PATCH v2] printk: add option to print cpu id To: "Pandita, Vikram" Cc: Venu Byravarasu , "gregkh@linuxfoundation.org" , "linux-kernel@vger.kernel.org" , Mike Turquette , Vimarsh Zutshi Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1475 Lines: 34 On Fri, Aug 3, 2012 at 11:36 AM, Pandita, Vikram wrote: > On Fri, Aug 3, 2012 at 2:32 AM, Venu Byravarasu wrote: >> As having Macro locally in the file of interest would serve the purpose, >> Why to change the printk code? > > As stated, the logic followed is exactly similar to well proven and > approved way to handle printk time stamp: CONFIG_PRINTK_TIME > Its an overhead on the system that enables the config option: > CONFIG_PRINTK_CPUID > Otherwise the system remains as is. > > To gain insight on SMP system logging behavior, the price to pay is > the extra 4 chars per printk line, > just like printk-time adds 15 chars to each line. Both options can be > disabled as desired. > > So i am not sure what kind of option you are proposing? > Do u imply PRINTK_TIME is not right then? It's 8 bytes per message for storing the timestamp in the records. There is never 15 bytes storage space needed, the prefix is constructed on-the-fly only while exporting the data. The CPU-ID would need at least two additional bytes (2^16 CPUS) in every record, unless it's a compile-time option. I can't tell, if everybody wants to pay the storage space for the the CPU-ID feature. Kay -- 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/