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{
    "id": 74276,
    "url": "http://patches.dpdk.org/api/covers/74276/?format=api",
    "web_url": "http://patches.dpdk.org/project/dpdk/cover/1594962519-20619-1-git-send-email-phil.yang@arm.com/",
    "project": {
        "id": 1,
        "url": "http://patches.dpdk.org/api/projects/1/?format=api",
        "name": "DPDK",
        "link_name": "dpdk",
        "list_id": "dev.dpdk.org",
        "list_email": "dev@dpdk.org",
        "web_url": "http://core.dpdk.org",
        "scm_url": "git://dpdk.org/dpdk",
        "webscm_url": "http://git.dpdk.org/dpdk",
        "list_archive_url": "https://inbox.dpdk.org/dev",
        "list_archive_url_format": "https://inbox.dpdk.org/dev/{}",
        "commit_url_format": ""
    },
    "msgid": "<1594962519-20619-1-git-send-email-phil.yang@arm.com>",
    "list_archive_url": "https://inbox.dpdk.org/dev/1594962519-20619-1-git-send-email-phil.yang@arm.com",
    "date": "2020-07-17T05:08:36",
    "name": "[v9,0/3] generic rte atomic APIs deprecate proposal",
    "submitter": {
        "id": 833,
        "url": "http://patches.dpdk.org/api/people/833/?format=api",
        "name": "Phil Yang",
        "email": "phil.yang@arm.com"
    },
    "mbox": "http://patches.dpdk.org/project/dpdk/cover/1594962519-20619-1-git-send-email-phil.yang@arm.com/mbox/",
    "series": [
        {
            "id": 11116,
            "url": "http://patches.dpdk.org/api/series/11116/?format=api",
            "web_url": "http://patches.dpdk.org/project/dpdk/list/?series=11116",
            "date": "2020-07-17T05:08:36",
            "name": "generic rte atomic APIs deprecate proposal",
            "version": 9,
            "mbox": "http://patches.dpdk.org/series/11116/mbox/"
        }
    ],
    "comments": "http://patches.dpdk.org/api/covers/74276/comments/",
    "headers": {
        "Return-Path": "<dev-bounces@dpdk.org>",
        "X-Original-To": "patchwork@inbox.dpdk.org",
        "Delivered-To": "patchwork@inbox.dpdk.org",
        "Received": [
            "from dpdk.org (dpdk.org [92.243.14.124])\n\tby inbox.dpdk.org (Postfix) with ESMTP id DD260A0528;\n\tFri, 17 Jul 2020 07:09:16 +0200 (CEST)",
            "from [92.243.14.124] (localhost [127.0.0.1])\n\tby dpdk.org (Postfix) with ESMTP id 169872C57;\n\tFri, 17 Jul 2020 07:09:15 +0200 (CEST)",
            "from foss.arm.com (foss.arm.com [217.140.110.172])\n by dpdk.org (Postfix) with ESMTP id 20E552C30\n for <dev@dpdk.org>; Fri, 17 Jul 2020 07:09:14 +0200 (CEST)",
            "from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14])\n by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 7ACCF1045;\n Thu, 16 Jul 2020 22:09:13 -0700 (PDT)",
            "from phil-VirtualBox.shanghai.arm.com\n (phil-VirtualBox.shanghai.arm.com [10.169.108.167])\n by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id C7EDA3F66E;\n Thu, 16 Jul 2020 22:09:09 -0700 (PDT)"
        ],
        "From": "Phil Yang <phil.yang@arm.com>",
        "To": "thomas@monjalon.net, john.mcnamara@intel.com,\n Honnappa.Nagarahalli@arm.com,\n drc@linux.vnet.ibm.com, dev@dpdk.org",
        "Cc": "david.marchand@redhat.com, jerinj@marvell.com,\n konstantin.ananyev@intel.com, Ola.Liljedahl@arm.com,\n bruce.richardson@intel.com, Ruifeng.Wang@arm.com, nd@arm.com",
        "Date": "Fri, 17 Jul 2020 13:08:36 +0800",
        "Message-Id": "<1594962519-20619-1-git-send-email-phil.yang@arm.com>",
        "X-Mailer": "git-send-email 2.7.4",
        "In-Reply-To": "<1594875225-5850-1-git-send-email-phil.yang@arm.com>",
        "References": "<1594875225-5850-1-git-send-email-phil.yang@arm.com>",
        "Subject": "[dpdk-dev] [PATCH v9 0/3] generic rte atomic APIs deprecate proposal",
        "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>,\n <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>,\n <mailto:dev-request@dpdk.org?subject=subscribe>",
        "Errors-To": "dev-bounces@dpdk.org",
        "Sender": "\"dev\" <dev-bounces@dpdk.org>"
    },
    "content": "DPDK provides generic rte_atomic APIs to do several atomic operations.\nThese APIs are using the deprecated __sync builtins and enforce full\nmemory barriers on aarch64. However, full barriers are not necessary\nin many use cases. In order to address such use cases, C language offers\nC11 atomic APIs. The C11 atomic APIs provide finer memory barrier control\nby making use of the memory ordering parameter provided by the user.\nVarious patches submitted in the past [2] and the patches in this series\nindicate significant performance gains on multiple aarch64 CPUs and no\nperformance loss on x86.\n\nBut the existing rte_atomic API implementations cannot be changed as the\nAPIs do not take the memory ordering parameter. The only choice available\nis replacing the usage of the rte_atomic APIs with C11 atomic APIs. In\norder to make this change, the following steps are proposed:\n\n[1] deprecate rte_atomic APIs so that future patches do not use rte_atomic\nAPIs (a script is added to flag the usages).\n[2] refactor the code that uses rte_atomic APIs to use c11 atomic APIs.\n\nThis patchset contains:\n1) changes to programmer guide describing writing efficient code for aarch64.\n2) the checkpatch script changes to flag rte_atomicNN_xxx and rte_smp_[r/w]mb\nAPIs usage in patches.\n3) wraps up __atomic_thread_fence with explicit memory ordering parameter.\n\nv9:\n1. Change built-ins to builtins. (David)\n2. Flag all the new code which use rte_atomicNN_xx and rte_smp_[r/w]mb.\n(Thomas/Honnappa)\n3. Simplify the warning output of the checkpatch script. (David)\n\nv8:\nMake descriptions more general. (Honnappa)\n\nv7:\n1. Remove code blocks in the guidance.\n2. Remove code reference links in the guidance.\n3. Remove the update of C11 atomics maintainers.\n\nv6:\nAdd check for rte_smp barriers APIs in the new code.\n\nv5:\n1. Wraps up __atomic_thread_fence to support optimized code for\n__ATOMIC_SEQ_CST memory order.\n2. Flag __atomic_thread_fence with __ATOMIC_SEQ_CST in new patches.\n3. Fix email address typo in patch 2/4.\n\nv4:\n1. add reader-writer concurrency case describing.\n2. claim maintainership of c11 atomics code for each platforms.\n3. flag rte_atomicNN_xxx in new patches for modules that have been converted to\nc11 style.\n4. flag __sync_xxx builtins in new patches.\n5. wraps up compiler atomic builtins\n6. move the changes of libraries which make use of c11 atomic APIs out of this\npatchset.\n\nv3:\nadd libatomic dependency for 32-bit clang\n\nv2:\n1. fix Clang '-Wincompatible-pointer-types' WARNING.\n2. fix typos.\n\nPhil Yang (3):\n  doc: add optimizations using C11 atomic builtins\n  devtools: prevent use of rte atomic APIs in future patches\n  eal/atomic: add wrapper for C11 atomic thread fence\n\n devtools/checkpatches.sh                         | 35 ++++++++++++++\n doc/guides/prog_guide/writing_efficient_code.rst | 59 +++++++++++++++++++++++-\n lib/librte_eal/arm/include/rte_atomic_32.h       |  6 +++\n lib/librte_eal/arm/include/rte_atomic_64.h       |  6 +++\n lib/librte_eal/include/generic/rte_atomic.h      |  6 +++\n lib/librte_eal/ppc/include/rte_atomic.h          |  6 +++\n lib/librte_eal/x86/include/rte_atomic.h          | 17 +++++++\n 7 files changed, 134 insertions(+), 1 deletion(-)"
}