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 BE72BC43334 for ; Wed, 29 Jun 2022 09:09:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231893AbiF2JJp convert rfc822-to-8bit (ORCPT ); Wed, 29 Jun 2022 05:09:45 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50974 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231184AbiF2JJk (ORCPT ); Wed, 29 Jun 2022 05:09:40 -0400 Received: from eu-smtp-delivery-151.mimecast.com (eu-smtp-delivery-151.mimecast.com [185.58.86.151]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 3443DD10E for ; Wed, 29 Jun 2022 02:09:39 -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-89-0bow6AXVPaapSvqyvZPCXg-1; Wed, 29 Jun 2022 10:09:36 +0100 X-MC-Unique: 0bow6AXVPaapSvqyvZPCXg-1 Received: from AcuMS.Aculab.com (fd9f:af1c:a25b:0:994c:f5c2:35d6:9b65) by AcuMS.aculab.com (fd9f:af1c:a25b:0:994c:f5c2:35d6:9b65) with Microsoft SMTP Server (TLS) id 15.0.1497.36; Wed, 29 Jun 2022 10:09:35 +0100 Received: from AcuMS.Aculab.com ([fe80::994c:f5c2:35d6:9b65]) by AcuMS.aculab.com ([fe80::994c:f5c2:35d6:9b65%12]) with mapi id 15.00.1497.036; Wed, 29 Jun 2022 10:09:35 +0100 From: David Laight To: 'Alexander Lobakin' , Albert Huang CC: "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Sebastian Andrzej Siewior , Menglong Dong , Petr Machata , "Kumar Kartikeya Dwivedi" , Arnd Bergmann , "Antoine Tenart" , Phil Auld , "Frederic Weisbecker" , Xin Long , "netdev@vger.kernel.org" , "linux-kernel@vger.kernel.org" Subject: RE: [PATCH] net : rps : supoort a single flow to use rps Thread-Topic: [PATCH] net : rps : supoort a single flow to use rps Thread-Index: AQHYiw+BtF4BFejA6Eeu6pKM0/Ynka1mGL6A Date: Wed, 29 Jun 2022 09:09:35 +0000 Message-ID: <2ed297c680f24879aba6f15df7630b96@AcuMS.aculab.com> References: <20220628140044.65068-1-huangjie.albert@bytedance.com> <20220628152956.1407334-1-alexandr.lobakin@intel.com> In-Reply-To: <20220628152956.1407334-1-alexandr.lobakin@intel.com> 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 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=C51A453 smtp.mailfrom=david.laight@aculab.com 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 .... > I'd suggest to use some flags bitfield instead, so it would be way > more scalable and at the same time have the pre-determined size. Ar > per several LKML discussions, `bool` may have different size and > logics depending on architecture and compiler, so when using it not > on the stack inside a function, but in a structure, it might be not > easy then to track cacheline layout etc. > So, maybe > > unsigned long rps_flags; > #define RPS_SINGLE_FLOW_ENABLE BIT(0) > > or even > > DECLARE_BITMAP(rps_flags); > #define RPS_SINGLE_FLOW_ENABLE 0 I don't think BITMAPs are a good idea unless you really need a lot of bits and (probably) locked accesses. You can use C bitfields - the compiler doesn't (usually) make too much of a 'pigs breakfast' of them unless you needs to set/test multiple ones at the same time. David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)