Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932377Ab2BJTdE (ORCPT ); Fri, 10 Feb 2012 14:33:04 -0500 Received: from mail-pw0-f46.google.com ([209.85.160.46]:37183 "EHLO mail-pw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932172Ab2BJTdC (ORCPT ); Fri, 10 Feb 2012 14:33:02 -0500 MIME-Version: 1.0 In-Reply-To: <20120210192714.GE4998@infradead.org> References: <1328873119-21553-1-git-send-email-jolsa@redhat.com> <1328895795.25989.29.camel@laptop> <20120210192714.GE4998@infradead.org> From: Linus Torvalds Date: Fri, 10 Feb 2012 11:32:42 -0800 X-Google-Sender-Auth: 15PxHoS-UeluadHIaisbm0o0tYc Message-ID: Subject: Re: [RFC 0/5] kernel: backtrace unwind support To: Arnaldo Carvalho de Melo Cc: Peter Zijlstra , Jiri Olsa , mingo@elte.hu, paulus@samba.org, cjashfor@linux.vnet.ibm.com, fweisbec@gmail.com, linux-kernel@vger.kernel.org, "James E.J. Bottomley" , Jan Blunck Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1179 Lines: 29 On Fri, Feb 10, 2012 at 11:27 AM, Arnaldo Carvalho de Melo wrote: > > "Vote for --fno-omit-frame-pointer! One register is a cheap price to pay > for not going insane!" > > /me goes back to non political things. Even with -fomit-frame-pointer (which seems to be a big deal on Atom in particular), the call frames really don't look that horrible even when we guess. And seeing the occasional stale pointer can often give hints about what the thing was doing before, so it's not even horrible. The biggest problem actually seems to often be some gcc versions that allocate a *lot* of stack space for some functions and then never really use it. That ends up then letting *tons* of really old stale code pointers "shine through". Sometimes it's our code that just has horrible stack usage with crazy worst-case allocations or something. We've fixed a few of them, it seems to be getting better. Linus -- 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/