Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752973Ab0ARQxI (ORCPT ); Mon, 18 Jan 2010 11:53:08 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752748Ab0ARQxH (ORCPT ); Mon, 18 Jan 2010 11:53:07 -0500 Received: from mx1.redhat.com ([209.132.183.28]:23549 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751151Ab0ARQxC (ORCPT ); Mon, 18 Jan 2010 11:53:02 -0500 Message-ID: <4B5491D0.20501@redhat.com> Date: Mon, 18 Jan 2010 18:52:32 +0200 From: Avi Kivity User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.5) Gecko/20091209 Fedora/3.0-4.fc12 Thunderbird/3.0 MIME-Version: 1.0 To: ananth@in.ibm.com CC: Pekka Enberg , Peter Zijlstra , Jim Keniston , Srikar Dronamraju , Ingo Molnar , Arnaldo Carvalho de Melo , utrace-devel , Frederic Weisbecker , Masami Hiramatsu , Maneesh Soni , Mark Wielaard , LKML Subject: Re: [RFC] [PATCH 1/7] User Space Breakpoint Assistance Layer (UBP) References: <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> <20100118154323.GA4424@in.ibm.com> In-Reply-To: <20100118154323.GA4424@in.ibm.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1176 Lines: 28 On 01/18/2010 05:43 PM, Ananth N Mavinakayanahalli wrote: >> >>> Well, the alternatives are very unappealing. Emulation and single-stepping >>> are going to be very slow compared to a couple of jumps. >>> >> So how big chunks of the address space are we talking here for uprobes? >> > As Srikar mentioned, the least we start with is 1 page. Though you can > have as many probes as you want, there are certain optimizations we can > do, depending on the most common usecases. > > For eg., if you'd consider the start of a routine to be the most > commonly traced location, most routines in a binary would generally > start with the same instruction (say push %ebp), and we can refcount a > slot with that instruction to be used for all probes of the same > instruction. > But then you can't follow the instruction with a jump back to the code... -- error compiling committee.c: too many arguments to function -- 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/