From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 54719 invoked by alias); 22 Mar 2016 16:41:16 -0000 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 Received: (qmail 54669 invoked by uid 89); 22 Mar 2016 16:41:16 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-1.9 required=5.0 tests=BAYES_00,SPF_HELO_PASS,T_RP_MATCHES_RCVD autolearn=ham version=3.3.2 spammy=Hx-languages-length:1625 X-HELO: mx1.redhat.com Received: from mx1.redhat.com (HELO mx1.redhat.com) (209.132.183.28) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with (AES256-GCM-SHA384 encrypted) ESMTPS; Tue, 22 Mar 2016 16:41:05 +0000 Received: from int-mx11.intmail.prod.int.phx2.redhat.com (int-mx11.intmail.prod.int.phx2.redhat.com [10.5.11.24]) by mx1.redhat.com (Postfix) with ESMTPS id B22E7627C4; Tue, 22 Mar 2016 16:41:04 +0000 (UTC) Received: from [127.0.0.1] (ovpn01.gateway.prod.ext.phx2.redhat.com [10.5.9.1]) by int-mx11.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id u2MGf3Dn010453; Tue, 22 Mar 2016 12:41:03 -0400 Subject: Re: JIT debugging (Attach and speed) To: Yichao Yu References: <56F168D7.9050405@redhat.com> <56F16F8F.9050404@redhat.com> Cc: gdb@sourceware.org, Paul Pluzhnikov From: Pedro Alves Message-ID: <56F1759F.3070100@redhat.com> Date: Tue, 22 Mar 2016 16:41:00 -0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.6.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit X-SW-Source: 2016-03/txt/msg00028.txt.bz2 On 03/22/2016 04:22 PM, Yichao Yu wrote: > On Tue, Mar 22, 2016 at 12:15 PM, Pedro Alves wrote: >> On 03/22/2016 03:46 PM, Pedro Alves wrote: > >> I re-read the 2011 discussion, and it seems like we had an idea for a fix: > > IIUC the proposed fix might cause regression in some cases? Yeah, there's no full fix available, only some ideas thrown out. The last discussed one wouldn't cause a regression -- the "longjmp"-caching idea. We may still need to defer breakpoint re-set to at most once per jit load event, something like Paul's original patch, but with a breakpoint_re_set call somewhere. It'd even be better to somehow restrict breakpoint re-setting to the jit modules that were added/removed/changed, but that's harder. > >>> >>> Do you know whether this happens with 7.11 and master, and if so, >>> would it be possible for you to git bisect the culprit? > > This is 7.11 package from ArchLinux. I could try bi-secting although > apparently you are faster at pin-point the issue. > >> >> Currently, jit_inferior_created_hook -> jit_inferior_init is only >> called when the inferior execs... >> >> Grepping around, I think that might have been >> the fix for PR gdb/13431 (03bef283c2d3): >> https://sourceware.org/ml/gdb-patches/2012-02/msg00023.html >> which removed the inferior_created (jit_inferior_created_observer). >> >> Adding an inferior_created observer back likely fixes the issue. > > I'm happy to test patches. I'm happy to provide guidance, but a fix would likely happen faster if someone else stepped up to write it. Thanks, Pedro Alves