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Marchesi" To: "Paul E. McKenney" Cc: Barret Rhoden , Josh Don , Hao Luo , davemarchevsky@meta.com, Tejun Heo , David Vernet , Neel Natu , Jack Humphries , bpf@vger.kernel.org, ast@kernel.org Subject: Re: BPF memory model In-Reply-To: <5b23c67b-8b15-4d54-8f38-c201a6842b20@paulmck-laptop> (Paul E. McKenney's message of "Mon, 16 Oct 2023 09:48:21 -0700") References: <33f06fa6-2f4d-4e50-a87e-0d6604d3c413@paulmck-laptop> <5c3b16c8-63e6-4f80-8fa2-6bacb38cdcb6@google.com> <22da941e-384a-4f02-80c4-8b84c0073f8d@google.com> <5b23c67b-8b15-4d54-8f38-c201a6842b20@paulmck-laptop> Date: Mon, 16 Oct 2023 19:17:54 +0200 Message-ID: <87o7gyqyf1.fsf@oracle.com> User-Agent: Gnus/5.13 (Gnus v5.13) Content-Type: text/plain X-ClientProxiedBy: LO4P265CA0191.GBRP265.PROD.OUTLOOK.COM (2603:10a6:600:311::19) To BYAPR10MB2888.namprd10.prod.outlook.com (2603:10b6:a03:88::32) Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: BYAPR10MB2888:EE_|CH3PR10MB6692:EE_ X-MS-Office365-Filtering-Correlation-Id: d93083ab-e6ae-42c2-70fc-08dbce6bd8f3 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:BYAPR10MB2888.namprd10.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230031)(366004)(346002)(136003)(396003)(39860400002)(376002)(230922051799003)(64100799003)(451199024)(186009)(1800799009)(66476007)(54906003)(66946007)(6916009)(66556008)(3480700007)(83380400001)(316002)(38100700002)(7416002)(2906002)(6666004)(4744005)(36756003)(6506007)(966005)(6486002)(53546011)(478600001)(4326008)(8676002)(8936002)(5930299018)(7116003)(41300700001)(26005)(2616005)(86362001)(5660300002)(6512007);DIR:OUT;SFP:1101; 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McKenney wrote: >> > Just to make sure that I understand, the idea is to compile from (say) >> > __atomic_load_n() to BPF instructions, correct? Or is this compiling all >> > the way to the target x86/ARMv8/whatever machine instructions? >> >> correct; i'm compiling with clang -target bpf to BPF instructions, which >> should be spitting out the appropriate BPF atomic ops. then i hope that if >> i get the compiler to emit the reads and writes in the correct order, that >> the JIT maintains that order when it turns them into x86/whatever. > > Hopefully better late than never, here is a draft: > > https://docs.google.com/document/d/1TaSEfWfLnRUi5KqkavUQyL2tThJXYWHS15qcbxIsFb0/edit?usp=sharing > > Please do feel free to add relevant comments. Nice :-) /me reads carefully