From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga02.intel.com (mga02.intel.com [134.134.136.20]) by dpdk.org (Postfix) with ESMTP id CDC5E1B945 for ; Fri, 11 Jan 2019 12:30:28 +0100 (CET) X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga005.fm.intel.com ([10.253.24.32]) by orsmga101.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 11 Jan 2019 03:30:27 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.56,465,1539673200"; d="scan'208";a="310995011" Received: from aburakov-mobl1.ger.corp.intel.com (HELO [10.251.85.183]) ([10.251.85.183]) by fmsmga005.fm.intel.com with ESMTP; 11 Jan 2019 03:30:25 -0800 To: Bruce Richardson Cc: Gage Eads , dev@dpdk.org, olivier.matz@6wind.com, arybchenko@solarflare.com, konstantin.ananyev@intel.com References: <20190110210122.24889-1-gage.eads@intel.com> <20190110210122.24889-2-gage.eads@intel.com> <20190111105848.GA18132@bricha3-MOBL.ger.corp.intel.com> From: "Burakov, Anatoly" Message-ID: <9b215f62-55e3-5ffd-d163-0a8c9e7fa55a@intel.com> Date: Fri, 11 Jan 2019 11:30:24 +0000 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.4.0 MIME-Version: 1.0 In-Reply-To: <20190111105848.GA18132@bricha3-MOBL.ger.corp.intel.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Subject: Re: [dpdk-dev] [PATCH 1/6] ring: change head and tail to pointer-width size X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 11 Jan 2019 11:30:29 -0000 On 11-Jan-19 10:58 AM, Bruce Richardson wrote: > On Fri, Jan 11, 2019 at 10:40:19AM +0000, Burakov, Anatoly wrote: >> <...> >> >>> + * Copyright(c) 2016-2019 Intel Corporation >>> */ >>> /** >>> @@ -88,7 +88,7 @@ rte_event_ring_enqueue_burst(struct rte_event_ring *r, >>> const struct rte_event *events, >>> unsigned int n, uint16_t *free_space) >>> { >>> - uint32_t prod_head, prod_next; >>> + uintptr_t prod_head, prod_next; >> >> I would also question the use of uinptr_t. I think semnatically, size_t is >> more appropriate. >> > Yes, it would, but I believe in this case they want to use the largest size > of (unsigned)int where there exists an atomic for manipulating 2 of them > simultaneously. [The largest size is to minimize any chance of an ABA issue > occuring]. Therefore we need 32-bit values on 32-bit and 64-bit on 64, and > I suspect the best way to guarantee this is to use pointer-sized values. If > size_t is guaranteed across all OS's to have the same size as uintptr_t it > could also be used, though. > > /Bruce > Technically, size_t and uintptr_t are not guaranteed to match. In practice, they won't match only on architectures that DPDK doesn't intend to run on (such as 16-bit segmented archs, where size_t would be 16-bit but uinptr_t would be 32-bit). In all the rest of DPDK code, we use size_t for this kind of thing. -- Thanks, Anatoly