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Mon, 1 Apr 2019 18:08:37 +0000 Received: from VE1PR08MB5149.eurprd08.prod.outlook.com ([fe80::e0ae:ecad:ec5:8177]) by VE1PR08MB5149.eurprd08.prod.outlook.com ([fe80::e0ae:ecad:ec5:8177%2]) with mapi id 15.20.1750.017; Mon, 1 Apr 2019 18:08:37 +0000 From: Honnappa Nagarahalli To: Gage Eads , "dev@dpdk.org" CC: "olivier.matz@6wind.com" , "arybchenko@solarflare.com" , "bruce.richardson@intel.com" , "konstantin.ananyev@intel.com" , "Gavin Hu (Arm Technology China)" , nd , "thomas@monjalon.net" , nd Thread-Topic: [PATCH v5 5/8] stack: add lock-free stack implementation Thread-Index: AQHU6B+85eb+XpPR/Ea/DTqfHPp9H6YnmxrA Date: Mon, 1 Apr 2019 18:08:37 +0000 Message-ID: References: <20190328180015.13878-1-gage.eads@intel.com> <20190401001238.17625-1-gage.eads@intel.com> <20190401001238.17625-6-gage.eads@intel.com> In-Reply-To: <20190401001238.17625-6-gage.eads@intel.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: authentication-results: spf=none (sender IP is ) smtp.mailfrom=Honnappa.Nagarahalli@arm.com; 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DIR:OUT; SFP:1101; SCL:1; SRVR:VE1PR08MB5215; H:VE1PR08MB5149.eurprd08.prod.outlook.com; FPR:; SPF:None; LANG:en; PTR:InfoNoRecords; A:1; MX:1; received-spf: None (protection.outlook.com: arm.com does not designate permitted sender hosts) x-ms-exchange-senderadcheck: 1 x-microsoft-antispam-message-info: +V907APgCnxO9dvFelVo+PyYQji0a1x8e3m7gG6HMYxG8abRSYVcHlgRt6Wh5QcMsin22YAPfrq7mfnWPH6xrnafn4y4hU//p79bewfsDXARtC70YvHAcFcm3Ro31Wp6OuMLHrygzmm2bDa3T+nm02kGJFInm93R8tkR0QWUXqjh1NBtaPx8sPo2Znz96rhF08qDCl5fdlYHm9AsY/qZsj0Ev5vLZuMpm3vs63VhoRGa2iDC3IXnPDhoVlVMs7NLE5DrVR77hGQcJ/gZYY1uxKl0SYvLcZxKxbbI3p7GFMhkqg0pchKqPc006ODUwR1RFWVis5iOQ4NFXRxJ2obHXxKRstqC1vcuoY5j8SAUhRP9pFj2x5Ti5c6JlpNUzVP8DnNx7dyg6S0T87jELyquUoqI2SHpssSRt3nF/CkW2pE= Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-OriginatorOrg: arm.com X-MS-Exchange-CrossTenant-Network-Message-Id: 6fcdb81d-17eb-48ce-f932-08d6b6cd1028 X-MS-Exchange-CrossTenant-originalarrivaltime: 01 Apr 2019 18:08:37.3904 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: f34e5979-57d9-4aaa-ad4d-b122a662184d X-MS-Exchange-CrossTenant-mailboxtype: HOSTED X-MS-Exchange-Transport-CrossTenantHeadersStamped: VE1PR08MB5215 Subject: Re: [dpdk-dev] [PATCH v5 5/8] stack: add lock-free stack implementation 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: , Errors-To: dev-bounces@dpdk.org Sender: "dev" Message-ID: <20190401180837.oVv5WyDH_xmvMqu4nAEIj15nd1J3WeeE9WpQ1Tt3EmE@z> > Subject: [PATCH v5 5/8] stack: add lock-free stack implementation >=20 > This commit adds support for a lock-free (linked list based) stack to the= stack > API. This behavior is selected through a new rte_stack_create() flag, > RTE_STACK_F_LF. >=20 > The stack consists of a linked list of elements, each containing a data p= ointer > and a next pointer, and an atomic stack depth counter. >=20 > The lock-free push operation enqueues a linked list of pointers by pointi= ng > the tail of the list to the current stack head, and using a CAS to swing = the > stack head pointer to the head of the list. The operation retries if it i= s > unsuccessful (i.e. the list changed between reading the head and modifyin= g > it), else it adjusts the stack length and returns. >=20 > The lock-free pop operation first reserves num elements by adjusting the > stack length, to ensure the dequeue operation will succeed without blocki= ng. > It then dequeues pointers by walking the list -- starting from the head -= - then > swinging the head pointer (using a CAS as well). While walking the list, = the > data pointers are recorded in an object table. >=20 > This algorithm stack uses a 128-bit compare-and-swap instruction, which > atomically updates the stack top pointer and a modification counter, to > protect against the ABA problem. >=20 > The linked list elements themselves are maintained in a lock-free LIFO li= st, > and are allocated before stack pushes and freed after stack pops. > Since the stack has a fixed maximum depth, these elements do not need to > be dynamically created. >=20 > Signed-off-by: Gage Eads > Reviewed-by: Olivier Matz > --- Reviewed-by: Honnappa Nagarahalli