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Thu, 5 Dec 2019 10:54:59 +0000 From: "Van Haaren, Harry" <harry.van.haaren@intel.com> To: Tom Barbette <barbette@kth.se>, Perugu Hemasai Chandra Prasad <hemasaiperugu@5g.iith.ac.in>, "users@dpdk.org" <users@dpdk.org>, "dev@dpdk.org" <dev@dpdk.org> Thread-Topic: [dpdk-users] [dpdk-dev] Sharing Data structure between logical cores in DPDK- regarding Thread-Index: AQHVq1jTg98jDMtzUkCQMa4FAm3g7qerXX1w Date: Thu, 5 Dec 2019 10:54:59 +0000 Message-ID: <MN2PR11MB44471C570BCC43F196D1048DD75C0@MN2PR11MB4447.namprd11.prod.outlook.com> References: <CALJSgO4nm83cgSThk5ksf_K-qRhx+OXsL9FvuMu4C33hsXekrw@mail.gmail.com> <1575542540897.56972@kth.se> In-Reply-To: <1575542540897.56972@kth.se> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-titus-metadata-40: eyJDYXRlZ29yeUxhYmVscyI6IiIsIk1ldGFkYXRhIjp7Im5zIjoiaHR0cDpcL1wvd3d3LnRpdHVzLmNvbVwvbnNcL0ludGVsMyIsImlkIjoiNjkyOTA4NGItNGNhYy00NTQwLWJlYTAtN2NmZjY1ZDk5YTAzIiwicHJvcHMiOlt7Im4iOiJDVFBDbGFzc2lmaWNhdGlvbiIsInZhbHMiOlt7InZhbHVlIjoiQ1RQX05UIn1dfV19LCJTdWJqZWN0TGFiZWxzIjpbXSwiVE1DVmVyc2lvbiI6IjE3LjEwLjE4MDQuNDkiLCJUcnVzdGVkTGFiZWxIYXNoIjoicVJGRjFQdFpyZXJaRVB2aDJDdkIyUml5RkFidVNVcUhVK3RUdTl1TDJDcXRXRVwvN0NIN2IzUUQ0QkZkRWw5NGYifQ== dlp-product: dlpe-windows dlp-reaction: no-action dlp-version: 11.2.0.6 x-ctpclassification: CTP_NT authentication-results: spf=none (sender IP is ) smtp.mailfrom=harry.van.haaren@intel.com; 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MX:1; A:1; x-ms-exchange-senderadcheck: 1 x-microsoft-antispam: BCL:0; x-microsoft-antispam-message-info: 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 x-ms-exchange-transport-forked: True Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-MS-Exchange-CrossTenant-Network-Message-Id: 5c6f3124-3825-40cd-577f-08d7797192e9 X-MS-Exchange-CrossTenant-originalarrivaltime: 05 Dec 2019 10:54:59.7466 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 46c98d88-e344-4ed4-8496-4ed7712e255d X-MS-Exchange-CrossTenant-mailboxtype: HOSTED X-MS-Exchange-CrossTenant-userprincipalname: hrxxsznebSUozVjbklXS4YX1kygm2L1Qu5jFuo8394AK3iXDHePNJK8EA0Z7ofW+r+ucsg6awF0OjpN6/ZAQkQBBsiAlhNSTEvJ5Bxl6y6I= X-MS-Exchange-Transport-CrossTenantHeadersStamped: MN2PR11MB3663 X-OriginatorOrg: intel.com Subject: Re: [dpdk-dev] [dpdk-users] Sharing Data structure between logical cores in DPDK- regarding X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: DPDK patches and discussions <dev.dpdk.org> List-Unsubscribe: <https://mails.dpdk.org/options/dev>, <mailto:dev-request@dpdk.org?subject=unsubscribe> List-Archive: <http://mails.dpdk.org/archives/dev/> List-Post: <mailto:dev@dpdk.org> List-Help: <mailto:dev-request@dpdk.org?subject=help> List-Subscribe: <https://mails.dpdk.org/listinfo/dev>, <mailto:dev-request@dpdk.org?subject=subscribe> Errors-To: dev-bounces@dpdk.org Sender: "dev" <dev-bounces@dpdk.org> > -----Original Message----- > From: users <users-bounces@dpdk.org> On Behalf Of Tom Barbette > Sent: Thursday, December 5, 2019 10:42 AM > To: Perugu Hemasai Chandra Prasad <hemasaiperugu@5g.iith.ac.in>; > users@dpdk.org; dev@dpdk.org > Subject: Re: [dpdk-users] [dpdk-dev] Sharing Data structure between logic= al > cores in DPDK- regarding >=20 > It depends on the datastructure. >=20 > If you use rte_hash, with the thread safety flags, it's safe. >=20 > In any case having a lot of cores accessing the same DS will lead to bad > performance. You should try to have per-core data structures whenever > possible. >=20 > Tom >=20 > ________________________________________ > De : dev <dev-bounces@dpdk.org> de la part de Perugu Hemasai Chandra Pras= ad > <hemasaiperugu@5g.iith.ac.in> > Envoy=E9 : jeudi 5 d=E9cembre 2019 11:16 > =C0 : users@dpdk.org; dev@dpdk.org > Objet : [dpdk-dev] Sharing Data structure between logical cores in DPDK- > regarding >=20 > Hi All, Hi! > I have a small doubt, can we share a data structure between > multiple logical cores in DPDK without locking? Note that "locking" and "atomic instructions" are not the same. So locking = a mutex is only one way of ensuring multiple cores have a coherent view on = the datastructure. The other method of doing "lock free" but multi-core safe data-structures i= s by using Atomic instructions, which ensure that results are observed corr= ectly on all cores accessing that data-structure. A good example is the Mul= ti-producer or Multi-consumer versions of the DPDK rte_ring ringbuffer. Regards, -Harry > I have tested it by sharing > a small structure with two variable and incrementing them in all logical > cores. It ran smooth I didn't get any issue. But I doubt if we can run it > for long time with some huge data structure having many elements getting > accessed by multiple logical cores. > Can anyone please clarify this. >=20 > Thanks and regards, > Hemasai.