From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1F408C54EE9 for ; Wed, 7 Sep 2022 08:03:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230243AbiIGIDa convert rfc822-to-8bit (ORCPT ); Wed, 7 Sep 2022 04:03:30 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45774 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230322AbiIGIDG (ORCPT ); Wed, 7 Sep 2022 04:03:06 -0400 Received: from eu-smtp-delivery-151.mimecast.com (eu-smtp-delivery-151.mimecast.com [185.58.85.151]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2EDE9AA3E5 for ; Wed, 7 Sep 2022 01:02:46 -0700 (PDT) Received: from AcuMS.aculab.com (156.67.243.121 [156.67.243.121]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384) id uk-mta-214-KBGl940hPP6SS3ocEhJz7A-1; Wed, 07 Sep 2022 09:02:44 +0100 X-MC-Unique: KBGl940hPP6SS3ocEhJz7A-1 Received: from AcuMS.Aculab.com (10.202.163.6) by AcuMS.aculab.com (10.202.163.6) with Microsoft SMTP Server (TLS) id 15.0.1497.38; Wed, 7 Sep 2022 09:02:42 +0100 Received: from AcuMS.Aculab.com ([::1]) by AcuMS.aculab.com ([::1]) with mapi id 15.00.1497.040; Wed, 7 Sep 2022 09:02:42 +0100 From: David Laight To: 'Peter Zijlstra' , Yury Norov CC: "linux-kernel@vger.kernel.org" , "Andy Shevchenko" , Rasmus Villemoes , Andrew Morton , Stephen Rothwell , Thomas Gleixner , "Paul E . McKenney" , "Vlastimil Babka" , Dmitry Vyukov , "Valentin Schneider" , Sander Vanheule , Alexey Klimov , Eric Biggers Subject: RE: [PATCH v2 1/5] smp: don't declare nr_cpu_ids if NR_CPUS == 1 Thread-Topic: [PATCH v2 1/5] smp: don't declare nr_cpu_ids if NR_CPUS == 1 Thread-Index: AQHYwgUQ3MtxNG+XS02hQI5PBTGTbq3TmwJA Date: Wed, 7 Sep 2022 08:02:42 +0000 Message-ID: <61fb5bada0be421abddc871908f8a3dd@AcuMS.aculab.com> References: <20220905230820.3295223-1-yury.norov@gmail.com> <20220905230820.3295223-2-yury.norov@gmail.com> In-Reply-To: Accept-Language: en-GB, en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-ms-exchange-transport-fromentityheader: Hosted x-originating-ip: [10.202.205.107] MIME-Version: 1.0 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: aculab.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Peter Zijlstra > Sent: 06 September 2022 15:37 ... > It was suggested the other day we remove a whole bunch of SMP=n code and > unconditionally use SMP code, even if its pointless on UP just to make > the source simpler. All the world isn't x86. There are some small embedded systems which are definitely UP and where you don't want any of the SMP 'bloat'. Architectures like NiosII will only ever be SMP. There certainly have recently been (and probably still are) small ppc cpu for embedded systems that are UP. David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)