From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755386AbYKKE7R (ORCPT ); Mon, 10 Nov 2008 23:59:17 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754574AbYKKE7E (ORCPT ); Mon, 10 Nov 2008 23:59:04 -0500 Received: from chilli.pcug.org.au ([203.10.76.44]:57871 "EHLO smtps.tip.net.au" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754389AbYKKE7C (ORCPT ); Mon, 10 Nov 2008 23:59:02 -0500 Date: Tue, 11 Nov 2008 15:58:44 +1100 From: Stephen Rothwell To: Andrew Morton Cc: Valdis.Kletnieks@vt.edu, linux-kernel@vger.kernel.org, Ken Chen , Ingo Molnar Subject: Re: 2.6.28-rc4-mmotm1110 - you gotta be kidding me... Message-Id: <20081111155844.7414bad8.sfr@canb.auug.org.au> In-Reply-To: <20081110193713.d94ed39a.akpm@linux-foundation.org> References: <30622.1226372137@turing-police.cc.vt.edu> <20081110193713.d94ed39a.akpm@linux-foundation.org> X-Mailer: Sylpheed 2.5.0 (GTK+ 2.12.11; i486-pc-linux-gnu) Mime-Version: 1.0 Content-Type: multipart/signed; protocol="application/pgp-signature"; micalg="PGP-SHA1"; boundary="Signature=_Tue__11_Nov_2008_15_58_44_+1100_9PPmursC.BFKkwS0" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --Signature=_Tue__11_Nov_2008_15_58_44_+1100_9PPmursC.BFKkwS0 Content-Type: text/plain; charset=US-ASCII Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Mon, 10 Nov 2008 19:37:13 -0800 Andrew Morton wrote: > > On Mon, 10 Nov 2008 21:55:37 -0500 Valdis.Kletnieks@vt.edu wrote: >=20 > > Somebody's been hitting the phunky pharmaceuticals in the last 4 days, > > because this ball-of-joy snuck into linux-next.patch sometime between > > -mmotm1106 and --mmotm1110. > >=20 > > Seen in a 'make silentallconfig' > >=20 > > Single-depth WCHAN output (SCHED_NO_NO_OMIT_FRAME_POINTER) [Y/n/?] (N= EW) ? > >=20 > > Calculate simpler /proc//wchan values. If this option > > is disabled then wchan values will recurse back to the > > caller function. This provides more accurate wchan values, > > at the expense of slightly more scheduling overhead. >=20 > I got lost here. >=20 > > If in doubt, say "Y". > >=20 > > So if I say 'y', is that a request to disable it, or enable it? And > > what exactly do I get if I vote *against* 'more accurate wchan values'? > > Do I get everybody having the same wchan pointing somewhere in the > > scheduler code, because that's where __builtin_return_address() points? > >=20 > > And please - a triple negative in the Kconfig variable name? This has > > gotta be a winner for poor taste in variable naming... > >=20 >=20 > Even if that is all sorted out, how the heck is anyone to decide > whether or not they need this thing? >=20 > Also, if we really really are so wishy-washy indecisive that we need to > make the function optional, it should if at all possible be made > runtime-configurable, not compile-time. This came from commit a87d091434ed2a34d647979ab12084139ee1fe41 ("x86, sched: enable wchan config menu item on 64-bit"). We have had CONFIG_SCHED_NO_NO_OMIT_FRAME_POINTER for some time on various architectures, this commit just made it available on x86_64 (by changing its dependency from X86_32 to X86). --=20 Cheers, Stephen Rothwell sfr@canb.auug.org.au http://www.canb.auug.org.au/~sfr/ --Signature=_Tue__11_Nov_2008_15_58_44_+1100_9PPmursC.BFKkwS0 Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.9 (GNU/Linux) iEYEARECAAYFAkkZEQQACgkQjjKRsyhoI8y1TwCdE/xpityLPrhe+i9Knk7PcRoO RIsAoL8CAlGl52VihOwaIO7dvNPZFwi1 =iVMv -----END PGP SIGNATURE----- --Signature=_Tue__11_Nov_2008_15_58_44_+1100_9PPmursC.BFKkwS0--