From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 1922 invoked by alias); 11 Dec 2009 16:42:43 -0000 Received: (qmail 1910 invoked by uid 22791); 11 Dec 2009 16:42:41 -0000 X-SWARE-Spam-Status: No, hits=-1.9 required=5.0 tests=AWL,BAYES_00,SARE_MSGID_LONG40,SPF_PASS X-Spam-Check-By: sourceware.org Received: from mail-ew0-f223.google.com (HELO mail-ew0-f223.google.com) (209.85.219.223) by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Fri, 11 Dec 2009 16:42:35 +0000 Received: by ewy23 with SMTP id 23so1271752ewy.4 for ; Fri, 11 Dec 2009 08:42:33 -0800 (PST) MIME-Version: 1.0 Received: by 10.213.96.195 with SMTP id i3mr1711079ebn.97.1260549750479; Fri, 11 Dec 2009 08:42:30 -0800 (PST) In-Reply-To: <947215.16059.qm@web112506.mail.gq1.yahoo.com> References: <816087.35180.qm@web112515.mail.gq1.yahoo.com> <4B218B30.4010501@vmware.com> <119734.20965.qm@web112506.mail.gq1.yahoo.com> <4B21B85F.1030502@vmware.com> <5e81cb500912101948nb8b09e8j7d58f6332ec62a38@mail.gmail.com> <008401ca7a3a$272f65f0$758e31d0$@com> <947215.16059.qm@web112506.mail.gq1.yahoo.com> Date: Fri, 11 Dec 2009 16:42:00 -0000 Message-ID: <5e81cb500912110842v5f2990ay9019e0ba4562d8c1@mail.gmail.com> Subject: Re: porting reversible on arm/mips From: Sean Chen To: paawan oza Cc: Jakob Engblom , Michael Snyder , Hui Zhu , gdb@sourceware.org Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable X-IsSubscribed: yes Mailing-List: contact gdb-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-owner@sourceware.org X-SW-Source: 2009-12/txt/msg00075.txt.bz2 On Fri, Dec 11, 2009 at 9:24 PM, paawan oza wrote: > I am not sure how arm can be drastically slower than x86 ! considering ar= m 32 bit. > but at the first point, if in some way if prec arch level stuff and abis = related framework are in place, > then optimization on the same may lead us to get faster recording like ca= che implementation and so on. > But I am not sure of any specific reason why on arm it could be very slow= er, having the same conf as x86. > > Regards, > Oza. > > > ----- Original Message ---- > From: Jakob Engblom > To: Sean Chen ; Michael Snyder > Cc: paawan oza ; Hui Zhu ; gdb@= sourceware.org > Sent: Fri, December 11, 2009 1:45:48 PM > Subject: RE: porting reversible on arm/mips > >> I was interested in the porting on ARM. But later I found that the >> performance impact on ARM might damage the usage of process record. In >> my experiment, reversible debugging is about 20000x slower, which >> might be endurable on the modern computer. However, ARM target is tens >> of times (or even more if we consider the memory) slower than PC. So >> recording instructions will be very slow, about thousands of >> instructions per second. > > I just must pitch in and say that it depends on the simulator. > > An advantage to using a full simulator is that you simplify the system an= d no > longer have to care about OS calls: the OS is just part of the context yo= u save > and reverse. =A0So the overhead actually goes down compared to native pre= c. =A0I > think a reversible ARM simulator can be made to run within a factor of te= n of > native speed, easily. > > > Best regards, > > /jakob > > _______________________________________________________ > > Jakob Engblom, PhD, Technical Marketing Manager > > Virtutech =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 Direct: +46 8 690 07 47 > Drottningholmsv=E4gen 22 =A0 =A0 =A0Mobile: +46 709 242 646 > 11243 Stockholm =A0 =A0 =A0 =A0 =A0 =A0 Web: =A0 =A0www.virtutech.com > Sweden > ________________________________________________________ > > > > I think ARM does be at least tens of times slower than x86. Image a PC and a phone, ARM architecture has to sacrifice the performance to gain the advantage of power and size saving. Here I assume that process record is more than 20000x slower on both x86 and ARM. I agree with you and believe this can be improved a lot in the future. --=20 Best Regards, Sean Chen