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GET /api/patches/55672/?format=api
HTTP 200 OK
Allow: GET, PUT, PATCH, HEAD, OPTIONS
Content-Type: application/json
Vary: Accept

{
    "id": 55672,
    "url": "http://patches.dpdk.org/api/patches/55672/?format=api",
    "web_url": "http://patches.dpdk.org/project/dpdk/patch/1561911676-37718-5-git-send-email-gavin.hu@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": "<1561911676-37718-5-git-send-email-gavin.hu@arm.com>",
    "list_archive_url": "https://inbox.dpdk.org/dev/1561911676-37718-5-git-send-email-gavin.hu@arm.com",
    "date": "2019-06-30T16:21:15",
    "name": "[RFC,4/5] spinlock: use wfe to reduce contention on aarch64",
    "commit_ref": null,
    "pull_url": null,
    "state": "superseded",
    "archived": true,
    "hash": "6f7dac8c9b43c01abc015f46cbe50639caf67a4c",
    "submitter": {
        "id": 1018,
        "url": "http://patches.dpdk.org/api/people/1018/?format=api",
        "name": "Gavin Hu",
        "email": "gavin.hu@arm.com"
    },
    "delegate": null,
    "mbox": "http://patches.dpdk.org/project/dpdk/patch/1561911676-37718-5-git-send-email-gavin.hu@arm.com/mbox/",
    "series": [
        {
            "id": 5234,
            "url": "http://patches.dpdk.org/api/series/5234/?format=api",
            "web_url": "http://patches.dpdk.org/project/dpdk/list/?series=5234",
            "date": "2019-06-30T16:21:11",
            "name": "use WFE for locks and ring on aarch64",
            "version": 1,
            "mbox": "http://patches.dpdk.org/series/5234/mbox/"
        }
    ],
    "comments": "http://patches.dpdk.org/api/patches/55672/comments/",
    "check": "success",
    "checks": "http://patches.dpdk.org/api/patches/55672/checks/",
    "tags": {},
    "related": [],
    "headers": {
        "Return-Path": "<dev-bounces@dpdk.org>",
        "X-Original-To": "patchwork@dpdk.org",
        "Delivered-To": "patchwork@dpdk.org",
        "Received": [
            "from [92.243.14.124] (localhost [127.0.0.1])\n\tby dpdk.org (Postfix) with ESMTP id 2D1991B99C;\n\tSun, 30 Jun 2019 18:21:53 +0200 (CEST)",
            "from foss.arm.com (foss.arm.com [217.140.110.172])\n\tby dpdk.org (Postfix) with ESMTP id B03171B995\n\tfor <dev@dpdk.org>; Sun, 30 Jun 2019 18:21:48 +0200 (CEST)",
            "from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14])\n\tby usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 30473344;\n\tSun, 30 Jun 2019 09:21:48 -0700 (PDT)",
            "from net-arm-thunderx2.shanghai.arm.com\n\t(net-arm-thunderx2.shanghai.arm.com [10.169.40.40])\n\tby usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id\n\t4BA453F718; Sun, 30 Jun 2019 09:21:46 -0700 (PDT)"
        ],
        "From": "Gavin Hu <gavin.hu@arm.com>",
        "To": "dev@dpdk.org",
        "Cc": "thomas@monjalon.net, jerinj@marvell.com, hemant.agrawal@nxp.com,\n\tbruce.richardson@intel.com, chaozhu@linux.vnet.ibm.com,\n\tHonnappa.Nagarahalli@arm.com, nd@arm.com, gavin.hu@arm.com",
        "Date": "Mon,  1 Jul 2019 00:21:15 +0800",
        "Message-Id": "<1561911676-37718-5-git-send-email-gavin.hu@arm.com>",
        "X-Mailer": "git-send-email 2.7.4",
        "In-Reply-To": "<1561911676-37718-1-git-send-email-gavin.hu@arm.com>",
        "References": "<1561911676-37718-1-git-send-email-gavin.hu@arm.com>",
        "Subject": "[dpdk-dev] [RFC 4/5] spinlock: use wfe to reduce contention on\n\taarch64",
        "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\t<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\t<mailto:dev-request@dpdk.org?subject=subscribe>",
        "Errors-To": "dev-bounces@dpdk.org",
        "Sender": "\"dev\" <dev-bounces@dpdk.org>"
    },
    "content": "In acquiring a spinlock, cores repeatedly poll the lock variable.\nThis is replaced by rte_wait_until_equal API.\n\n20% performance gain was measured by running spinlock_autotest on 14\nisolated cores of ThunderX2.\n\nSigned-off-by: Gavin Hu <gavin.hu@arm.com>\nReviewed-by: Ruifeng Wang <ruifeng.wang@arm.com>\nReviewed-by: Phil Yang <phil.yang@arm.com>\nReviewed-by: Steve Capper <steve.capper@arm.com>\nReviewed-by: Ola Liljedahl <ola.liljedahl@arm.com>\nReviewed-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>\n---\n .../common/include/arch/arm/rte_spinlock.h         | 25 ++++++++++++++++++++++\n .../common/include/generic/rte_spinlock.h          |  2 +-\n 2 files changed, 26 insertions(+), 1 deletion(-)",
    "diff": "diff --git a/lib/librte_eal/common/include/arch/arm/rte_spinlock.h b/lib/librte_eal/common/include/arch/arm/rte_spinlock.h\nindex 1a6916b..b7e8521 100644\n--- a/lib/librte_eal/common/include/arch/arm/rte_spinlock.h\n+++ b/lib/librte_eal/common/include/arch/arm/rte_spinlock.h\n@@ -16,6 +16,31 @@ extern \"C\" {\n #include <rte_common.h>\n #include \"generic/rte_spinlock.h\"\n \n+/* armv7a does support WFE, but an explicit wake-up signal using SEV is\n+ * required (must be preceded by DSB to drain the store buffer) and\n+ * this is less performant, so keep armv7a implementation unchanged.\n+ */\n+#if defined(RTE_USE_WFE) && defined(RTE_ARCH_ARM64)\n+static inline void\n+rte_spinlock_lock(rte_spinlock_t *sl)\n+{\n+\tunsigned int tmp;\n+\t/* http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.\n+\t * faqs/ka16809.html\n+\t */\n+\tasm volatile(\n+\t\t\"sevl\\n\"\n+\t\t\"1:\t wfe\\n\"\n+\t\t\"2:\t ldaxr   %w0, %1\\n\"\n+\t\t\"cbnz   %w0, 1b\\n\"\n+\t\t\"stxr   %w0, %w2, %1\\n\"\n+\t\t\"cbnz   %w0, 2b\\n\"\n+\t\t: \"=&r\" (tmp), \"+Q\"(sl->locked)\n+\t\t: \"r\" (1)\n+\t\t: \"cc\", \"memory\");\n+}\n+#endif\n+\n static inline int rte_tm_supported(void)\n {\n \treturn 0;\ndiff --git a/lib/librte_eal/common/include/generic/rte_spinlock.h b/lib/librte_eal/common/include/generic/rte_spinlock.h\nindex 87ae7a4..cf4f15b 100644\n--- a/lib/librte_eal/common/include/generic/rte_spinlock.h\n+++ b/lib/librte_eal/common/include/generic/rte_spinlock.h\n@@ -57,7 +57,7 @@ rte_spinlock_init(rte_spinlock_t *sl)\n static inline void\n rte_spinlock_lock(rte_spinlock_t *sl);\n \n-#ifdef RTE_FORCE_INTRINSICS\n+#if defined(RTE_FORCE_INTRINSICS) && !defined(RTE_USE_WFE)\n static inline void\n rte_spinlock_lock(rte_spinlock_t *sl)\n {\n",
    "prefixes": [
        "RFC",
        "4/5"
    ]
}