From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1764563AbYD2TKf (ORCPT ); Tue, 29 Apr 2008 15:10:35 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1763896AbYD2TJx (ORCPT ); Tue, 29 Apr 2008 15:09:53 -0400 Received: from relay1.sgi.com ([192.48.171.29]:37431 "EHLO relay.sgi.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1763850AbYD2TJw (ORCPT ); Tue, 29 Apr 2008 15:09:52 -0400 Date: Tue, 29 Apr 2008 12:09:51 -0700 (PDT) From: Christoph Lameter X-X-Sender: clameter@schroedinger.engr.sgi.com To: Arjan van de Ven cc: Ingo Molnar , akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Linus Torvalds , Peter Zijlstra Subject: Re: [2/2] vmallocinfo: Add caller information In-Reply-To: <20080428140026.32aaf3bf@infradead.org> Message-ID: References: <20080318222701.788442216@sgi.com> <20080318222827.519656153@sgi.com> <20080429084854.GA14913@elte.hu> <20080428124849.4959c419@infradead.org> <20080428140026.32aaf3bf@infradead.org> 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 On Mon, 28 Apr 2008, Arjan van de Ven wrote: > > Hmmm... Why do we have CONFIG_FRAMEPOINTER then? > > to make the backtraces more accurate. Well so we display out of whack backtraces? There are also issues on platforms that do not have a stack in the classic sense (rotating register file on IA64 and Sparc64 f.e.). Determining a backtrace can be very expensive. > > The current implementation of vmalloc_caller() follows what we have > > done with kmalloc_track_caller. Its low overhead and always on. > > stacktraces aren't entirely free, the cost is O(nr of modules) unfortunately ;( The current implementation /proc/vmallocinfo avoids these issues and with just one caller address it can print one line per vmalloc request.