Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758604AbZFSAcm (ORCPT ); Thu, 18 Jun 2009 20:32:42 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751028AbZFSAce (ORCPT ); Thu, 18 Jun 2009 20:32:34 -0400 Received: from hrndva-omtalb.mail.rr.com ([71.74.56.124]:54758 "EHLO hrndva-omtalb.mail.rr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750939AbZFSAcd (ORCPT ); Thu, 18 Jun 2009 20:32:33 -0400 Date: Thu, 18 Jun 2009 20:32:34 -0400 (EDT) From: Steven Rostedt X-X-Sender: rostedt@gandalf.stny.rr.com To: Jeremy Fitzhardinge cc: Jake Edge , LKML , Ingo Molnar , Frederic Weisbecker Subject: Re: problem with function_graph self-test? In-Reply-To: <4A3ADBFA.1060702@goop.org> Message-ID: References: <20090616122603.6a628097@chukar> <4A3ADBFA.1060702@goop.org> User-Agent: Alpine 2.00 (DEB 1167 2008-08-23) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1828 Lines: 45 On Thu, 18 Jun 2009, Jeremy Fitzhardinge wrote: > > > > This is something that gcc is screwing with us. After spending all day > > today trying to figure out what is happening, I finally found it in the > > assembly. > > > > In the timer_stats_update_stats function, I get this at the beginning: > > > > 00000327 : > > 327: 57 push %edi > > 328: 8d 7c 24 08 lea 0x8(%esp),%edi > > 32c: 83 e4 e0 and $0xffffffe0,%esp > > 32f: ff 77 fc pushl 0xfffffffc(%edi) > > 332: 55 push %ebp > > 333: 89 e5 mov %esp,%ebp > > 335: 57 push %edi > > 336: 56 push %esi > > 337: 53 push %ebx > > 338: 81 ec 8c 00 00 00 sub $0x8c,%esp > > 33e: e8 fc ff ff ff call 33f > > 33f: R_386_PC32 mcount > > > > > > And this at the end of the function: > > > > 4f6: 8d 67 f8 lea 0xfffffff8(%edi),%esp > > 4f9: 5f pop %edi > > 4fa: c3 ret > > > > Something to do with using _RET_IP_ in spin_unlock_irqrestore() perhaps? No, it was the fact that there was a local variable of type struct entry, where entry was defined to be ____cacheline_aligned_in_smp. But that was not the end of it. It happens throughout the code. The next hit was in tcp_ack(). But it has something to do with -Os on i386. -- Steve -- 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/