From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from co9outboundpool.messaging.microsoft.com (co9ehsobe005.messaging.microsoft.com [207.46.163.28]) (using TLSv1 with cipher AES128-SHA (128/128 bits)) (Client CN "mail.global.frontbridge.com", Issuer "MSIT Machine Auth CA 2" (not verified)) by ozlabs.org (Postfix) with ESMTPS id AF0552C00E2 for ; Wed, 20 Nov 2013 10:43:40 +1100 (EST) Message-ID: <1384904608.1403.395.camel@snotra.buserror.net> Subject: Re: [PATCH] lib/crc32: slice by 4 is more efficient than the default slice by 8 on Powerpc 8xx. From: Scott Wood To: Joakim Tjernlund Date: Tue, 19 Nov 2013 17:43:28 -0600 In-Reply-To: References: <20131118070423.E47181A4D3D@localhost.localdomain> <1384885766.1403.366.camel@snotra.buserror.net> Content-Type: text/plain; charset="UTF-8" MIME-Version: 1.0 Cc: Christophe Leroy , Marcelo Tosatti , Bob Pearson , linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Wed, 2013-11-20 at 00:39 +0100, Joakim Tjernlund wrote: > Scott Wood wrote on 2013/11/19 19:29:26: > > > > I don't think we should go littering the Kconfig with defaults for > > various bits of hardware -- especially since you've already pointed out > > non-8xx hardware that would also want this. Put it in defconfig > > instead, unless you can identify very broad classes of machines for > > which SLICEBY4 is faster. > > hmm, when 64bits went in there was not much proof that it was faster for > a wide range of CPU, just 2 or 3 if I recall correctly. I suspect there > are quite a few CPUs where 32 bits a equal or faster. That may be the case, but I don't think we want a big list of them in lib/Kconfig. Whether the default should change (for all targets that don't override it in defconfig, or at least for some broader category such as "all 32-bit chips") is a different discussion. -Scott