From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id 03F57A6E for ; Wed, 7 Sep 2016 16:10:53 +0000 (UTC) Received: from mx1.redhat.com (mx1.redhat.com [209.132.183.28]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id B29E710A for ; Wed, 7 Sep 2016 16:10:52 +0000 (UTC) Message-ID: <1473264649.10218.56.camel@redhat.com> From: Rik van Riel To: Shuah Khan , Andy Lutomirski Date: Wed, 07 Sep 2016 12:10:49 -0400 In-Reply-To: References: <20160906185143.GF2356@ZenIV.linux.org.uk> <20160906152243.766f3845@gandalf.local.home> <20160906213644.GA16732@p183.telecom.by> <20160906175343.2f0d9135@gandalf.local.home> <20160906224100.GA17212@p183.telecom.by> <20160907051039.GG2356@ZenIV.linux.org.uk> Content-Type: multipart/signed; micalg="pgp-sha256"; protocol="application/pgp-signature"; boundary="=-VLJKQwGjtu0Tt9Av/wk/" Mime-Version: 1.0 Cc: ksummit-discuss@lists.linuxfoundation.org Subject: Re: [Ksummit-discuss] [topic proposal] tracepoints and ABI stability warranties List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , --=-VLJKQwGjtu0Tt9Av/wk/ Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Wed, 2016-09-07 at 09:30 -0600, Shuah Khan wrote: > On Tue, Sep 6, 2016 at 11:30 PM, Andy Lutomirski > wrote: > >=C2=A0 > > I wouldn't mind a policy that tracepoints are simply never > > stable.=C2=A0=C2=A0Maybe we > > should even deliberately change them periodically to drive the > > point home. > >=20 > > The kernel should be able to have a debug API that is genuinely for > > *debugging* and doesn't freeze the underlying implementation. > Agreed. Tracepoints and events provide a powerful tool in debug > certain class > of problems (races and performance problems) where traditional debug > methods > such as CONFIG_DEBUG_FOO aren't effective. Trace information includes > important > status information on thread status which is helpful in debugging. =46rom an enterprise distro (and user) point of view, it is important to be able to debug a kernel that is running on a production system (and developed some problem after a month of running), without having to reboot into a special "debug kernel". Being able to just fire up a tracer debugging script that can identify intermittent problems is an invaluable tool in making the kernel better for our users. Hamstringing our ability to make the kernel better, in order to keep the debugging ABI stable, is shooting ourselves (and our users) in the foot. --=20 All rights reversed --=-VLJKQwGjtu0Tt9Av/wk/ Content-Type: application/pgp-signature; name="signature.asc" Content-Description: This is a digitally signed message part Content-Transfer-Encoding: 7bit -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iQEcBAABCAAGBQJX0DwKAAoJEM553pKExN6DvasIALL8VIgAQ+fqQ69rZz2I8T1g dpm7Fv0kCDEYKgj0uGDGx8szXhqPKjcmu042C+TUHXkmsTayjrU3dW9JXTiPhSRj PE3Jly4Zgy7WQ0RvRnMCwKynqPHXAZFu14qLOe9D+vnu49XPeTNfDzAwlRhkK+Fu 8O1GycqLpV+/wjpysazEgO4YJTF0EkWHrYH0ac3k+J28V4LgMvGVR55slRna65ea JT5pXeENkuwTPAEpvqSYn+IuqwaY773schDjZ9nTVc5KN8y6ab4qEmWKhMRKKRw0 vVDac7qZZMb6tczUN1GYAsfvurpiaPjB8U11XZ+/9yfM7d5ywvNGlOUZxMnaMXU= =kRh0 -----END PGP SIGNATURE----- --=-VLJKQwGjtu0Tt9Av/wk/--