From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 7692 invoked by alias); 12 Nov 2009 01:18:02 -0000 Received: (qmail 7657 invoked by uid 22791); 12 Nov 2009 01:18:01 -0000 X-SWARE-Spam-Status: No, hits=-2.4 required=5.0 tests=AWL,BAYES_00,SPF_PASS X-Spam-Check-By: sourceware.org Received: from imr2.ericy.com (HELO imr2.ericy.com) (198.24.6.3) by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Thu, 12 Nov 2009 01:17:57 +0000 Received: from eusrcmw751.eamcs.ericsson.se (eusrcmw751.exu.ericsson.se [138.85.77.51]) by imr2.ericy.com (8.13.1/8.13.1) with ESMTP id nAC1Htdv014508; Wed, 11 Nov 2009 19:17:55 -0600 Received: from eusrcmw751.eamcs.ericsson.se ([138.85.77.56]) by eusrcmw751.eamcs.ericsson.se with Microsoft SMTPSVC(6.0.3790.3959); Wed, 11 Nov 2009 19:17:21 -0600 Received: from eusaamw0711.eamcs.ericsson.se ([147.117.20.178]) by eusrcmw751.eamcs.ericsson.se with Microsoft SMTPSVC(6.0.3790.3959); Wed, 11 Nov 2009 19:17:21 -0600 Received: from EUSAACMS0703.eamcs.ericsson.se ([169.254.1.4]) by eusaamw0711.eamcs.ericsson.se ([147.117.20.178]) with mapi; Wed, 11 Nov 2009 20:17:20 -0500 From: Marc Khouzam To: Michael Snyder CC: "gdb@sourceware.org" Date: Thu, 12 Nov 2009 21:07:00 -0000 Subject: RE: real world reverse debugging success story Message-ID: References: <4AFB54CA.9090900@vmware.com> <4AFB5F43.3030908@vmware.com> <4AFB5FDD.7010008@vmware.com> In-Reply-To: <4AFB5FDD.7010008@vmware.com> Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 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: 2009-11/txt/msg00134.txt.bz2 =20 > -----Original Message----- > From: Michael Snyder [mailto:msnyder@vmware.com]=20 > Sent: November-11-09 8:08 PM > To: Michael Snyder > Cc: Marc Khouzam; gdb@sourceware.org > Subject: Re: real world reverse debugging success story >=20 > Michael Snyder wrote: > > Marc Khouzam wrote: > >> [...] > >>> Stats: used an 8 million instruction cache, running as a > >>> ring buffer. Had to record over 80 million instructions > >>> before I tripped the bug. Saved core file with record log > >>> was 250 megabytes, and reloaded fine. > >> Very impressive! > >> > >> How was the responsiveness? I assume you didn't step > >> over all those instuctions ;-) So, you must have run the program > >> and have it be recorded for a while. I'm wondering if the=20 > execution > >> was annoyingly slow, or if it was ok. > >=20 > > The record phase was kind of slow, but I'm sure that was > > impacted by a very large number of notifications to the effect > > that process record would not record some memory because it > > could not get the segment register. > >=20 > > Replay was not bad at all, about 15 seconds to get from > > "goto-bookmark begin" to "goto-bookmark end". For 80 > > million instructions, that's about 5 million insns / sec. You know what, it just dawned on me that I never really payed attention to the replaying spead :-O I'm glad to hear it is good. It is really the recording speed that I'm curious about. I think right now, this is a big limiting factor (understandably of course), that would prevent the use of PRecord for real world applications. I've had one person want to use PRecord to learn about a piece of software. They figured that they would record execution up to a point in the code they know would hit, and then could go backwards to find a more proper starting point for their investigation. But the recording was to slow to allow the application to reach far enough fast enough. I was happy to see that Hui had some ideas on how to improve the recording speed. This reverse 'thingy' as so much potential! :-) > >=20 > > Much faster than a first gen IBM PC, for instance! ;-) >=20 > Oh, sorry, it was 8 million insns, so about 0.5M / sec. >=20 >=20