From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga11.intel.com (mga11.intel.com [192.55.52.93]) by dpdk.org (Postfix) with ESMTP id E50F095EB for ; Tue, 23 Dec 2014 10:23:11 +0100 (CET) Received: from orsmga003.jf.intel.com ([10.7.209.27]) by fmsmga102.fm.intel.com with ESMTP; 23 Dec 2014 01:23:10 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.04,691,1406617200"; d="scan'208";a="503040249" Received: from unknown ([10.243.20.17]) by orsmga003.jf.intel.com with SMTP; 23 Dec 2014 01:18:29 -0800 Received: by (sSMTP sendmail emulation); Tue, 23 Dec 2014 09:23:08 +0025 Date: Tue, 23 Dec 2014 09:23:08 +0000 From: Bruce Richardson To: "Walukiewicz, Miroslaw" Message-ID: <20141223092307.GA10244@bricha3-MOBL3> References: <7C4248CAE043B144B1CD242D275626532FE232BA@IRSMSX104.ger.corp.intel.com> <7C4248CAE043B144B1CD242D275626532FE27C3B@IRSMSX104.ger.corp.intel.com> <20141219100342.GA3848@bricha3-MOBL3> <20141222094603.GA1768@bricha3-MOBL3> <20141222102852.7e6d5e81@urahara> <7C4248CAE043B144B1CD242D275626532FE29694@IRSMSX104.ger.corp.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <7C4248CAE043B144B1CD242D275626532FE29694@IRSMSX104.ger.corp.intel.com> Organization: Intel Shannon Ltd. User-Agent: Mutt/1.5.23 (2014-03-12) Cc: "dev@dpdk.org" Subject: Re: [dpdk-dev] [RFC PATCH 0/7] support multi-phtread per lcore X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: patches and discussions about DPDK List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 23 Dec 2014 09:23:12 -0000 On Tue, Dec 23, 2014 at 09:19:54AM +0000, Walukiewicz, Miroslaw wrote: > > > > -----Original Message----- > > From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Stephen > > Hemminger > > Sent: Monday, December 22, 2014 7:29 PM > > To: Richardson, Bruce > > Cc: dev@dpdk.org > > Subject: Re: [dpdk-dev] [RFC PATCH 0/7] support multi-phtread per lcore > > > > On Mon, 22 Dec 2014 09:46:03 +0000 > > Bruce Richardson wrote: > > > > > On Mon, Dec 22, 2014 at 01:51:27AM +0000, Liang, Cunming wrote: > > > > ... > > > > > I'm conflicted on this one. However, I think far more applications would > > be > > > > > broken > > > > > to start having to use thread_id in place of an lcore_id than would be > > broken > > > > > by having the lcore_id no longer actually correspond to a core. > > > > > I'm actually struggling to come up with a large number of scenarios > > where it's > > > > > important to an app to determine the cpu it's running on, compared to > > the large > > > > > number of cases where you need to have a data-structure per thread. > > In DPDK > > > > > libs > > > > > alone, you see this assumption that lcore_id == thread_id a large > > number of > > > > > times. > > > > > > > > > > Despite the slight logical inconsistency, I think it's better to avoid > > introducing > > > > > a thread-id and continue having lcore_id representing a unique thread. > > > > > > > > > > /Bruce > > > > > > > > Ok, I understand it. > > > > I list the implicit meaning if using lcore_id representing the unique thread. > > > > 1). When lcore_id less than RTE_MAX_LCORE, it still represents the logical > > core id. > > > > 2). When lcore_id large equal than RTE_MAX_LCORE, it represents an > > unique id for thread. > > > > 3). Most of APIs(except rte_lcore_id()) in rte_lcore.h suggest to be used > > only in CASE 1) > > > > 4). rte_lcore_id() can be used in CASE 2), but the return value no matter > > represent a logical core id. > > > > > > > > If most of us feel it's acceptable, I'll prepare for the RFC v2 base on this > > conclusion. > > > > > > > > /Cunming > > > > > > Sorry, I don't like that suggestion either, as having lcore_id values greater > > > than RTE_MAX_LCORE is terrible, as how will people know how to > > dimension arrays > > > to be indexes by lcore id? Given the choice, if we are not going to just use > > > lcore_id as a generic thread id, which is always between 0 and > > RTE_MAX_LCORE > > > we can look to define a new thread_id variable to hold that. However, it > > should > > > have a bounded range. > > > From an ease-of-porting perspective, I still think that the simplest option is > > to > > > use the existing lcore_id and accept the fact that it's now a thread id rather > > > than an actual physical lcore. Question is, is would that cause us lots of > > issues > > > in the future? > > > > > > /Bruce > > > > The current rte_lcore_id() has different meaning the thread. Your proposal > > will > > break code that uses lcore_id to do per-cpu statistics and the lcore_config > > code in the samples. > > q > It depends on application context and how application treats rte_lcore_id() core. When number of the threads will not exceed the number of cores (let's say old-fashioned DPDK application) all stuff like per-cpu statistics will work correctly. > > When we treat threads on cores as ordinary threads as we introducing the special function rte_pthread_create() - the meaning of rte_lcore_id() changes to indicate > thread number what is correct under new assumptions and new application model. > > I do not want to limit DPDK design to only per-cpu application. There is much more application models that could be supported using DPDK. > Current per-cpu approach is only a subset of the possible applications. > > Maybe we should indicate something like CONFIG_RTE_PTHREAD_ENABLE to change a meaning of rte_lcore_id() and introducing rte_pthread_create() family. > > Mirek > >>From the discussion it does look to me like we do need a separate thread id value, separate from core id. Unfortunately that means that many(most?) places in libs and examples where we use lcore_id right now, we probably need to use the new thread id. :-( /Bruce