From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga01.intel.com (mga01.intel.com [192.55.52.88]) by dpdk.org (Postfix) with ESMTP id 2A8E195EB for ; Tue, 23 Dec 2014 10:19:58 +0100 (CET) Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by fmsmga101.fm.intel.com with ESMTP; 23 Dec 2014 01:19:56 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.07,630,1413270000"; d="scan'208";a="641831093" Received: from irsmsx102.ger.corp.intel.com ([163.33.3.155]) by fmsmga001.fm.intel.com with ESMTP; 23 Dec 2014 01:19:55 -0800 Received: from irsmsx104.ger.corp.intel.com ([169.254.5.209]) by IRSMSX102.ger.corp.intel.com ([169.254.2.213]) with mapi id 14.03.0195.001; Tue, 23 Dec 2014 09:19:55 +0000 From: "Walukiewicz, Miroslaw" To: Stephen Hemminger , "Richardson, Bruce" Thread-Topic: [dpdk-dev] [RFC PATCH 0/7] support multi-phtread per lcore Thread-Index: AQHQFOb74ekE1aZuS0qI47KzEksKLpyKJ0pQgAFMagCABQyCsIAAEV2AgAS8XBCAAN6IgIAAj96AgAQtdYCAAISagIAAkhMAgAD1zEA= Date: Tue, 23 Dec 2014 09:19:54 +0000 Message-ID: <7C4248CAE043B144B1CD242D275626532FE29694@IRSMSX104.ger.corp.intel.com> References: <1418263490-21088-1-git-send-email-cunming.liang@intel.com> <7C4248CAE043B144B1CD242D275626532FE15298@IRSMSX104.ger.corp.intel.com> <7C4248CAE043B144B1CD242D275626532FE232BA@IRSMSX104.ger.corp.intel.com> <7C4248CAE043B144B1CD242D275626532FE27C3B@IRSMSX104.ger.corp.intel.com> <20141219100342.GA3848@bricha3-MOBL3> <20141222094603.GA1768@bricha3-MOBL3> <20141222102852.7e6d5e81@urahara> In-Reply-To: <20141222102852.7e6d5e81@urahara> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [163.33.239.181] Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 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 09:19:58 -0000 > -----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 >=20 > On Mon, 22 Dec 2014 09:46:03 +0000 > Bruce Richardson wrote: >=20 > > 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 =3D=3D thread_id a lar= ge > number of > > > > times. > > > > > > > > Despite the slight logical inconsistency, I think it's better to av= oid > introducing > > > > a thread-id and continue having lcore_id representing a unique thre= ad. > > > > > > > > /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 lo= gical > 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 ma= tter > 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 g= reater > > 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 jus= t 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, i= t > should > > have a bounded range. > > From an ease-of-porting perspective, I still think that the simplest op= tion 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 >=20 > The current rte_lcore_id() has different meaning the thread. Your proposa= l > will > break code that uses lcore_id to do per-cpu statistics and the lcore_conf= ig > 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 wil= l work correctly.=20 When we treat threads on cores as ordinary threads as we introducing the sp= ecial function rte_pthread_create() - the meaning of rte_lcore_id() changes= to indicate=20 thread number what is correct under new assumptions and new application mo= del. 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.=20 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.=20 Mirek