From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755035Ab1AVAEn (ORCPT ); Fri, 21 Jan 2011 19:04:43 -0500 Received: from 74-93-104-97-Washington.hfc.comcastbusiness.net ([74.93.104.97]:54346 "EHLO sunset.davemloft.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755013Ab1AVAEl (ORCPT ); Fri, 21 Jan 2011 19:04:41 -0500 Date: Fri, 21 Jan 2011 16:05:16 -0800 (PST) Message-Id: <20110121.160516.256850550.davem@davemloft.net> To: mathieu.desnoyers@efficios.com Cc: linux-kernel@vger.kernel.org, rostedt@goodmis.org, fweisbec@gmail.com, mingo@elte.hu, richm@oldelvet.org.uk, ben@decadent.org.uk, sparclinux@vger.kernel.org Subject: Re: [patch 3/3] tracepoints: use __u64_aligned/U64_ALIGN() From: David Miller In-Reply-To: <20110121203643.046218322@efficios.com> References: <20110121203630.725922272@efficios.com> <20110121203643.046218322@efficios.com> X-Mailer: Mew version 6.3 on Emacs 23.1 / Mule 6.0 (HANACHIRUSATO) Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Mathieu Desnoyers Date: Fri, 21 Jan 2011 15:36:33 -0500 > commit 7e066fb870fcd1025ec3ba7bbde5d541094f4ce1 added the aligned(32) type and > variable attribute to the tracepoint structures to deal with gcc happily > aligning statically defined structures on 32-byte multiples. > > Working on issues within Ftrace, we came up with __64_aligned, which deals with > this issue more elegantly by forcing an 8-byte alignment to both the type > declaration and variable definition. > > This therefore saves space, bringing down the size of struct tracepoint from 64 > bytes to 38 on 64-bit architectures. > > Updating: > - The type attribute (for iteration over the struct tracepoint array) > - Added the variable attribute to the extern definition (needed to force gcc to > consider this alignment for the following definition) > - The definition variable attribute (to force gcc to this specific alignment for > the static definitions) > - The linker script (8-byte alignment can now replace the previous 32-byte > alignment for the custom tracepoint section) > > Signed-off-by: Mathieu Desnoyers Acked-by: David S. Miller