Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755322Ab0ARMYj (ORCPT ); Mon, 18 Jan 2010 07:24:39 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755095Ab0ARMYi (ORCPT ); Mon, 18 Jan 2010 07:24:38 -0500 Received: from casper.infradead.org ([85.118.1.10]:51757 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755242Ab0ARMYh (ORCPT ); Mon, 18 Jan 2010 07:24:37 -0500 Subject: Re: [RFC] [PATCH 1/7] User Space Breakpoint Assistance Layer (UBP) From: Peter Zijlstra To: Avi Kivity Cc: Pekka Enberg , ananth@in.ibm.com, Jim Keniston , Srikar Dronamraju , Ingo Molnar , Arnaldo Carvalho de Melo , utrace-devel , Frederic Weisbecker , Masami Hiramatsu , Maneesh Soni , Mark Wielaard , LKML In-Reply-To: <4B545146.3080001@redhat.com> References: <20100111122521.22050.3654.sendpatchset@srikar.in.ibm.com> <4B5325CF.5000001@redhat.com> <1263740593.557.20967.camel@twins> <4B53661A.9090907@redhat.com> <1263800752.4283.19.camel@laptop> <4B543F93.3060509@redhat.com> <1263815072.4283.305.camel@laptop> <4B544D7C.2060708@redhat.com> <1263816396.4283.361.camel@laptop> <4B544F8E.1080603@redhat.com> <84144f021001180413w76a8ca2axb0b9f07ee4dea67e@mail.gmail.com> <4B545146.3080001@redhat.com> Content-Type: text/plain; charset="UTF-8" Date: Mon, 18 Jan 2010 13:24:05 +0100 Message-ID: <1263817445.4283.408.camel@laptop> Mime-Version: 1.0 X-Mailer: Evolution 2.28.1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 881 Lines: 21 On Mon, 2010-01-18 at 14:17 +0200, Avi Kivity wrote: > On 01/18/2010 02:13 PM, Pekka Enberg wrote: > > So how big chunks of the address space are we talking here for uprobes? > > > > That's for the authors to answer, but at a guess, 32 bytes per probe > (largest x86 instruction is 15 bytes), so 32 MB will give you a million > probes. That's a piece of cake for x86-64, probably harder to justify > for i386. Yeah, I'm aware of people turning off address space randomization to gain more virtual space on i386, I'm pretty sure those folks aren't going to be happy if we shrink it. Let alone them trying to probe their app. -- 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/