From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755969AbZFAOgl (ORCPT ); Mon, 1 Jun 2009 10:36:41 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754754AbZFAOg3 (ORCPT ); Mon, 1 Jun 2009 10:36:29 -0400 Received: from bombadil.infradead.org ([18.85.46.34]:56542 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756352AbZFAOg2 (ORCPT ); Mon, 1 Jun 2009 10:36:28 -0400 Date: Mon, 1 Jun 2009 10:36:26 -0400 From: Christoph Hellwig To: Li Zefan Cc: Steven Rostedt , Frederic Weisbecker , Ingo Molnar , LKML Subject: Re: [PATCH] tracing/irq: use softirq_to_name instead of __print_symbolic Message-ID: <20090601143626.GA26981@infradead.org> References: <4A2396C7.3000700@cn.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4A2396C7.3000700@cn.fujitsu.com> User-Agent: Mutt/1.5.18 (2008-05-17) X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jun 01, 2009 at 04:52:23PM +0800, Li Zefan wrote: > It's great to boost recording of softirq events, but why not simply > use softirq_to_name in TP_printk()? Because userspace programs using the binary trace buffer have no chance to retrieve the values from softirq_to_name. > The above commit has 2 flaws: > > - we waste memory defining local static struct trace_print_flags array > in each softirq TRACE_EVENT That could be solved by declaring the array manually and just passing the address to __print_symbolic. Steve, would that work? (also for __print_flags) > - if someone adds/removes a softirq, he may not know show_softirq_name() > needs to be updated Just make sure you have the translation defined next to the actual flags. This is what I do in the XFS tracer: typedef enum xfs_alloctype { XFS_ALLOCTYPE_ANY_AG, /* allocate anywhere, use rotor */ XFS_ALLOCTYPE_FIRST_AG, /* ... start at ag 0 */ XFS_ALLOCTYPE_START_AG, /* anywhere, start in this a.g. */ XFS_ALLOCTYPE_THIS_AG, /* anywhere in this a.g. */ XFS_ALLOCTYPE_START_BNO, /* near this block else anywhere */ XFS_ALLOCTYPE_NEAR_BNO, /* in this a.g. and near this block */ XFS_ALLOCTYPE_THIS_BNO /* at exactly this block */ } xfs_alloctype_t; #define XFS_ALLOC_TYPES \ { XFS_ALLOCTYPE_ANY_AG, "ANY_AG" }, \ { XFS_ALLOCTYPE_FIRST_AG, "FIRST_AG" }, \ { XFS_ALLOCTYPE_START_AG, "START_AG" }, \ { XFS_ALLOCTYPE_THIS_AG, "THIS_AG" }, \ { XFS_ALLOCTYPE_START_BNO, "START_BNO" }, \ { XFS_ALLOCTYPE_NEAR_BNO, "NEAR_BNO" }, \ { XFS_ALLOCTYPE_THIS_BNO, "THIS_BNO" } > Another issue with the above commit, that the output of softirq events > becomes: > > X-1701 [000] 1595.220739: softirq_entry: softirq=1 action=TIMER_SOFTIRQ > > Compared to the original output: > > X-1701 [000] 1595.220739: softirq_entry: softirq=1 action=TIMER Which is trivially fixable, see above :)