From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: <konstantin.ananyev@intel.com> Received: from mga03.intel.com (mga03.intel.com [134.134.136.65]) by dpdk.org (Postfix) with ESMTP id 73B7B19F5 for <dev@dpdk.org>; Thu, 8 Jan 2015 18:05:57 +0100 (CET) Received: from fmsmga002.fm.intel.com ([10.253.24.26]) by orsmga103.jf.intel.com with ESMTP; 08 Jan 2015 09:02:32 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.07,723,1413270000"; d="scan'208";a="658836745" Received: from irsmsx101.ger.corp.intel.com ([163.33.3.153]) by fmsmga002.fm.intel.com with ESMTP; 08 Jan 2015 09:05:53 -0800 Received: from irsmsx105.ger.corp.intel.com ([169.254.7.195]) by IRSMSX101.ger.corp.intel.com ([169.254.1.126]) with mapi id 14.03.0195.001; Thu, 8 Jan 2015 17:05:48 +0000 From: "Ananyev, Konstantin" <konstantin.ananyev@intel.com> To: "Liang, Cunming" <cunming.liang@intel.com>, Stephen Hemminger <stephen@networkplumber.org>, "Richardson, Bruce" <bruce.richardson@intel.com> Thread-Topic: [dpdk-dev] [RFC PATCH 0/7] support multi-phtread per lcore Thread-Index: AQHQFOb7rWYcSWZpW0S0EaABVQ+aIpyKJ7GAgAFMAwCABRIMAIAAC9OAgAS+ioCAANxagIAAj96AgAQtdYCAAISagIAAkhMAgAEB6QCAGXpCEA== Date: Thu, 8 Jan 2015 17:05:48 +0000 Message-ID: <2601191342CEEE43887BDE71AB977258213D39EA@irsmsx105.ger.corp.intel.com> References: <1418263490-21088-1-git-send-email-cunming.liang@intel.com> <7C4248CAE043B144B1CD242D275626532FE15298@IRSMSX104.ger.corp.intel.com> <D0158A423229094DA7ABF71CF2FA0DA31188B881@shsmsx102.ccr.corp.intel.com> <7C4248CAE043B144B1CD242D275626532FE232BA@IRSMSX104.ger.corp.intel.com> <D0158A423229094DA7ABF71CF2FA0DA31188C928@shsmsx102.ccr.corp.intel.com> <7C4248CAE043B144B1CD242D275626532FE27C3B@IRSMSX104.ger.corp.intel.com> <D0158A423229094DA7ABF71CF2FA0DA31188E454@shsmsx102.ccr.corp.intel.com> <20141219100342.GA3848@bricha3-MOBL3> <D0158A423229094DA7ABF71CF2FA0DA31188EF9F@shsmsx102.ccr.corp.intel.com> <20141222094603.GA1768@bricha3-MOBL3> <20141222102852.7e6d5e81@urahara> <D0158A423229094DA7ABF71CF2FA0DA31188F9AD@shsmsx102.ccr.corp.intel.com> In-Reply-To: <D0158A423229094DA7ABF71CF2FA0DA31188F9AD@shsmsx102.ccr.corp.intel.com> Accept-Language: en-IE, en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [163.33.239.180] Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Cc: "dev@dpdk.org" <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 <dev.dpdk.org> List-Unsubscribe: <http://dpdk.org/ml/options/dev>, <mailto:dev-request@dpdk.org?subject=unsubscribe> List-Archive: <http://dpdk.org/ml/archives/dev/> List-Post: <mailto:dev@dpdk.org> List-Help: <mailto:dev-request@dpdk.org?subject=help> List-Subscribe: <http://dpdk.org/ml/listinfo/dev>, <mailto:dev-request@dpdk.org?subject=subscribe> X-List-Received-Date: Thu, 08 Jan 2015 17:05:58 -0000 Hi Steve, > -----Original Message----- > From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Liang, Cunming > Sent: Tuesday, December 23, 2014 9:52 AM > To: Stephen Hemminger; Richardson, Bruce > Cc: dev@dpdk.org > Subject: Re: [dpdk-dev] [RFC PATCH 0/7] support multi-phtread per lcore >=20 >=20 >=20 > > -----Original Message----- > > From: Stephen Hemminger [mailto:stephen@networkplumber.org] > > Sent: Tuesday, December 23, 2014 2:29 AM > > To: Richardson, Bruce > > Cc: Liang, Cunming; 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 <bruce.richardson@intel.com> 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 application= s would be > > > > > broken > > > > > to start having to use thread_id in place of an lcore_id than wou= ld 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 scenari= os where > > it's > > > > > important to an app to determine the cpu it's running on, compare= d to the > > large > > > > > number of cases where you need to have a data-structure per threa= d. In > > DPDK > > > > > libs > > > > > alone, you see this assumption that lcore_id =3D=3D thread_id a l= arge 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 th= read. > > > > > > > > > > /Bruce > > > > > > > > Ok, I understand it. > > > > I list the implicit meaning if using lcore_id representing the uniq= ue 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 b= e 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 bas= e 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 dimens= ion > > arrays > > > to be indexes by lcore id? Given the choice, if we are not going to j= ust 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 lo= ts of issues > > > in the future? > > > > > > /Bruce > > > > The current rte_lcore_id() has different meaning the thread. Your propo= sal will > > break code that uses lcore_id to do per-cpu statistics and the lcore_co= nfig > > code in the samples. > > q > [Liang, Cunming] +1. Few more thoughts on that subject: Actually one more place in the lib, where lcore_id is used (and it should b= e unique): rte_spinlock_recursive_lock() / rte_spinlock_recursive_trylock(). So if we going to replace lcore_id with thread_id as uniques thread index, = then these functions have to be updated too. About maintaining our own unique thread_id inside shared memory (_get_linea= r_tid()/_put_linear_tid()). There is one thing that worries me with that approach: In case of abnormal process termination, TIDs used by that process will rem= ain 'reserved' and there is no way to know which TIDs were used by terminated process. So there could be a situation with DPDK multi-process model, when after secondary process abnormal termination, It wouldn't be possible = to restart it - we just run out of 'free' TIDs.=20 =20 Which makes me think probably there is no need to introduce new globally un= ique 'thread_id'? Might be just lcore_id is enough? =20 As Mirek and Bruce suggested we can treat it a sort of 'unique thread id' i= nside EAL. Or as 'virtual' core id that can run on set of physical cpus, and these sub= sets for different 'virtual' cores can intersect. Then basically we can keep legacy behaviour with '-c <lcores_mask>,' where = each lcore_id matches one to one with physical cpu, and introduce new one, some= thing like: --lcores=3D'(<lcore_set1>)=3D(<phys_cpu_set1>),..(<lcore_setN)=3D(<phys_cpu= _setN>)'. So let say: --lcores=3D(0-7)=3D(0,2-4),(10)=3D(7),(8)=3D(all)' would mean: Create 10 EAL threads, bind threads with clore_id=3D[0-7] to cpuset: <0,2,3= ,4>,=20 thread with lcore_id=3D10 is binded to cpu 7, and allow to run lcore_id= =3D8 on any cpu in the system. =20 Of course '-c' and '-lcores' would be mutually exclusive, and we will need = to update rte_lcore_to_socket_id() and introduce: rte_lcore_(set|get)_affinity(). Does it make sense to you? BTW, one more thing: while we are on it - it is probably a good time to do= something with our interrupt thread? It is a bit strange that we can't use rte_pktmbuf_free() or rte_spinlock_r= ecursive_lock() from our own interrupt/alarm handlers Konstantin