From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: <dev-bounces@dpdk.org> Received: from dpdk.org (dpdk.org [92.243.14.124]) by dpdk.space (Postfix) with ESMTP id 4193FA00E6 for <public@inbox.dpdk.org>; Wed, 17 Apr 2019 03:45:16 +0200 (CEST) Received: from [92.243.14.124] (localhost [127.0.0.1]) by dpdk.org (Postfix) with ESMTP id 3BFAF1B57F; Wed, 17 Apr 2019 03:45:15 +0200 (CEST) Received: from EUR04-VI1-obe.outbound.protection.outlook.com (mail-eopbgr80052.outbound.protection.outlook.com [40.107.8.52]) by dpdk.org (Postfix) with ESMTP id 984BA1B57E for <dev@dpdk.org>; Wed, 17 Apr 2019 03:45:13 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=armh.onmicrosoft.com; s=selector1-arm-com; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=XkH4gGjCRFlzAfZ5SYXdE2qeemgnM+pd38BbkzC7rBk=; b=D6z09HY4IXHJPAX8n/fw0pV11MFSf+m180Wn/W3XQXhaNQ7FIOrrpz8dP+Oh7gO+w2LdwNGCaSZS7x6Zsmh4PB7jRdNBmWlzR7vW2GxbRc2R/nFFJLdLXiCj6NacVvrxkRULOhPxjwQInrl/KNMWLRgCN9BEzmm+wWUU68znPCo= Received: from VE1PR08MB5149.eurprd08.prod.outlook.com (20.179.30.152) by VE1PR08MB4702.eurprd08.prod.outlook.com (10.255.114.146) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.1792.18; Wed, 17 Apr 2019 01:45:11 +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 15.20.1792.018; Wed, 17 Apr 2019 01:45:11 +0000 From: Honnappa Nagarahalli <Honnappa.Nagarahalli@arm.com> To: Stephen Hemminger <stephen@networkplumber.org> CC: "Ananyev, Konstantin" <konstantin.ananyev@intel.com>, "paulmck@linux.ibm.com" <paulmck@linux.ibm.com>, "Kovacevic, Marko" <marko.kovacevic@intel.com>, "dev@dpdk.org" <dev@dpdk.org>, "Gavin Hu (Arm Technology China)" <Gavin.Hu@arm.com>, Dharmik Thakkar <Dharmik.Thakkar@arm.com>, Malvika Gupta <Malvika.Gupta@arm.com>, Honnappa Nagarahalli <Honnappa.Nagarahalli@arm.com>, nd <nd@arm.com>, nd <nd@arm.com> Thread-Topic: [PATCH v5 1/3] rcu: add RCU library supporting QSBR mechanism Thread-Index: AQHU8XwL9ZW9vcwT20K3DuZSwCCMIqY5FWOAgASrdlSAAIGtIIAAowaAgAAhIcCAAEs7gIAAIfHQ Date: Wed, 17 Apr 2019 01:45:11 +0000 Message-ID: <VE1PR08MB514983BE886E05A7CAB277D298250@VE1PR08MB5149.eurprd08.prod.outlook.com> References: <20181122033055.3431-1-honnappa.nagarahalli@arm.com> <20190412202039.46902-1-honnappa.nagarahalli@arm.com> <20190412202039.46902-2-honnappa.nagarahalli@arm.com> <20190412150650.3709358e@shemminger-XPS-13-9360> <VE1PR08MB51497C4B9E164CD07AC6EB5298280@VE1PR08MB5149.eurprd08.prod.outlook.com> <20190412160629.670eacd1@shemminger-XPS-13-9360> <2601191342CEEE43887BDE71AB9772580148A97E53@irsmsx105.ger.corp.intel.com> <20190415083834.31b38ed3@shemminger-XPS-13-9360> <2601191342CEEE43887BDE71AB9772580148A98064@irsmsx105.ger.corp.intel.com> <20190415142631.4c250248@shemminger-XPS-13-9360> <VE1PR08MB5149AA5C4CAC61DB42E286CF98240@VE1PR08MB5149.eurprd08.prod.outlook.com> <20190416075415.76c9d64a@xps13.lan> <VE1PR08MB5149930C88AA75010836986598240@VE1PR08MB5149.eurprd08.prod.outlook.com> <20190416142205.5d683e8e@xps13.lan> In-Reply-To: <20190416142205.5d683e8e@xps13.lan> 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:VE1PR08MB4702; 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: fC0beB+ygIJ/juUtvFMBkuiMLNrOqPR44v8DOQ6SypzGKab4vPHc8I9oKhZnMXMXphoFUGh8RBCmzAcVbf17Zo9oWF8alK7dOEiDXb/MUul3tJZi4oNJVUbNPiY3Mq70JPgY0Wv/sblSrhnf94G04gan5pjYD1FAbQxk8JO3ZYyH4btm7BT8ylbwCBYVkw+jhGG2eagcuf5VG2Y9YuVPbkck+JhhzhCM6ddOOF7IoHdDVFddHO+82BxNWRUN47iyW7/2TQlZhVa47l2D0CotcdY0AvfGpSejhUzdb8o5J+U7iMVVrJjx7DkDBcTPHz1njsn6hPQ/6rQDLQ/VSag060+QAJ8bU+nTNWkBN5lfXFwDAogJmk1gJ1Ucsx2T83KKCIDIUdgEYFVpYsk7ah9ihqKQabWNqKm098OsZD84+TE= 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: 148f61f5-ce6f-43d3-c17e-08d6c2d6545b X-MS-Exchange-CrossTenant-originalarrivaltime: 17 Apr 2019 01:45:11.1982 (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: VE1PR08MB4702 Subject: Re: [dpdk-dev] [PATCH v5 1/3] rcu: add RCU library supporting QSBR mechanism 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> Message-ID: <20190417014511.ulnEVEEGZL3kn-5yvnnOSoKqe2KROZn42o1lSQJkyRk@z> > > > > > > > > > > > > > > > > > > > > > > After evaluating long term API/ABI issues, I think > > > > > > > > > > > you need to get rid of almost all use of inline and > > > > > > > > > > > visible structures. Yes it might be marginally > > > > > > > > > > > slower, but you thank me > > > > > the first time you have to fix something. > > > > > > > > > > > > > > > > > > > > > Agree, I was planning on another version to address > > > > > > > > > > this (I am yet > > > > > to take a look at your patch addressing the ABI). > > > > > > > > > > The structure visibility definitely needs to be address= ed. > > > > > > > > > > For the inline functions, is the plan to convert all > > > > > > > > > > the inline functions in DPDK? If yes, I think we need > > > > > > > > > > to consider the performance > > > > > > > > > difference. May be consider L3-fwd application, change > > > > > > > > > all the > > > > > inline functions in its path and run a test? > > > > > > > > > > > > > > > > > > Every function that is not in the direct datapath should > > > > > > > > > not be > > > > > inline. > > > > > > > > > Exceptions or things like rx/tx burst, ring > > > > > > > > > enqueue/dequeue, and packet alloc/free > > > > I do not understand how DPDK can claim ABI compatibility if we > > > > have > > > inline functions (unless we freeze any development in these inline > > > functions forever). > > > > > > > > > > > > > > > > > > > > Plus synchronization routines: spin/rwlock/barrier, etc. > > > > > > > > I think rcu should be one of such exceptions - it is just > > > > > > > > another synchronization mechanism after all (just a bit > > > > > > > > more > > > sophisticated). > > > > > > > > Konstantin > > > > > > > > > > > > > > If you look at the other userspace RCU, you wil see that the > > > > > > > only inlines are the rcu_read_lock,rcu_read_unlock and > > > > > rcu_reference/rcu_assign_pointer. > > > > > > > > > > > > > > The synchronization logic is all real functions. > > > > > > > > > > > > In fact, I think urcu provides both flavors: > > > > > > https://github.com/urcu/userspace- > > > > > rcu/blob/master/include/urcu/static/ > > > > > > urcu-qsbr.h I still don't understand why we have to treat it > > > > > > differently then let say spin-lock/ticket-lock or rwlock. > > > > > > If we gone all the way to create our own version of rcu, we > > > > > > probably want it to be as fast as possible (I know that main > > > > > > speedup should come from the fact that readers don't have to > > > > > > wait for writer to finish, but still...) > > > > > > > > > > > > Konstantin > > > > > > > > > > > > > > > > Having locking functions inline is already a problem in current > releases. > > > > > The implementation can not be improved without breaking ABI (or > > > > > doing special workarounds like lock v2) > > > > I think ABI and inline function discussion needs to be taken up in > > > > a > > > different thread. > > > > > > > > Currently, I am looking to hide the structure visibility. I looked > > > > at your > > > patch [1], it is a different case than what I have in this patch. It > > > is a pretty generic use case as well (similar situation exists in > > > other libraries). I think a generic solution should be agreed upon. > > > > > > > > If we have to hide the structure content, the handle to QS > > > > variable > > > returned to the application needs to be opaque. I suggest using 'void= *' > > > behind which any structure can be used. > > > > > > > > typedef void * rte_rcu_qsbr_t; > > > > typedef void * rte_hash_t; > > > > > > > > But it requires typecasting. > > > > > > > > [1] http://patchwork.dpdk.org/cover/52609/ > > > > > > C allows structure to be defined without knowing what is in it > therefore. > > > > > > typedef struct rte_rcu_qsbr rte_rcu_qsbr_t; > > > > > > is preferred (or do it without typedef) > > > > > > struct rte_rcu_qsbr; > > > > I see that rte_hash library uses the same approach (struct rte_hash in > rte_hash.h, though it is marking as internal). But the ABI Laboratory too= l > [1] seems to be reporting incorrect numbers for this library even though > the internal structure is changed. > > > > [1] > > https://abi- > laboratory.pro/index.php?view=3Dcompat_report&l=3Ddpdk&v1=3D19.0 > > 2&v2=3Dcurrent&obj=3D66794&kind=3Dabi >=20 > The problem is rte_hash structure is exposed as part of ABI in > rte_cuckoo_hash.h This was a mistake. Do you mean, due to the use of structure with the same name? I am wondering= if it is just a tools issue. The application is not supposed to include rt= e_cuckoo_hash.h. For the RCU library, we either need to go all functions or leave it the way= it is. I do not see a point in trying to hide the internal structure while= having inline functions. I converted the inline functions to function calls. Testing on Arm platform (results *are* repeatable) shows very minimal drop = (0.1% to 0.2%) in performance while using lock-free rte_hash data structure= . But one of the test cases which is just spinning shows good amount of dro= p (41%). Testing on x86 (Xeon Gold 6132 CPU @ 2.60GHz, results *are* pretty repeatab= le) shows performance improvements (7% to 8%) while using lock-free rte_has= h data structure. The test cases which is just spinning show significant dr= op (14%, 155%, 231%). Konstantin, any thoughts on the results? I will send out V6 which will fix issues reported so far. The function vs i= nline part is still open, need to close it soon.