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GET /api/patches/79051/?format=api
{ "id": 79051, "url": "https://patches.dpdk.org/api/patches/79051/?format=api", "web_url": "https://patches.dpdk.org/project/dpdk/patch/20200928190334.40624-2-honnappa.nagarahalli@arm.com/", "project": { "id": 1, "url": "https://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": "<20200928190334.40624-2-honnappa.nagarahalli@arm.com>", "list_archive_url": "https://inbox.dpdk.org/dev/20200928190334.40624-2-honnappa.nagarahalli@arm.com", "date": "2020-09-28T19:03:28", "name": "[v2,2/8] net/memif: relax the load of ring tail pointer for M2S ring", "commit_ref": null, "pull_url": null, "state": "accepted", "archived": true, "hash": "f7911fc838c0689323c9af218bd3143c92f9ef3f", "submitter": { "id": 1045, "url": "https://patches.dpdk.org/api/people/1045/?format=api", "name": "Honnappa Nagarahalli", "email": "honnappa.nagarahalli@arm.com" }, "delegate": { "id": 319, "url": "https://patches.dpdk.org/api/users/319/?format=api", "username": "fyigit", "first_name": "Ferruh", "last_name": "Yigit", "email": "ferruh.yigit@amd.com" }, "mbox": "https://patches.dpdk.org/project/dpdk/patch/20200928190334.40624-2-honnappa.nagarahalli@arm.com/mbox/", "series": [ { "id": 12563, "url": "https://patches.dpdk.org/api/series/12563/?format=api", "web_url": "https://patches.dpdk.org/project/dpdk/list/?series=12563", "date": "2020-09-28T19:03:27", "name": "[v2,1/8] net/memif: do not update local copy of tail in tx function", "version": 2, "mbox": "https://patches.dpdk.org/series/12563/mbox/" } ], "comments": "https://patches.dpdk.org/api/patches/79051/comments/", "check": "success", "checks": "https://patches.dpdk.org/api/patches/79051/checks/", "tags": {}, "related": [], "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 EB584A04DB;\n\tMon, 28 Sep 2020 21:04:32 +0200 (CEST)", "from [92.243.14.124] (localhost [127.0.0.1])\n\tby dpdk.org (Postfix) with ESMTP id 80FFD1D69D;\n\tMon, 28 Sep 2020 21:04:10 +0200 (CEST)", "from foss.arm.com (foss.arm.com [217.140.110.172])\n by dpdk.org (Postfix) with ESMTP id EBA1A1D66B;\n Mon, 28 Sep 2020 21:04:06 +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 45D51113E;\n Mon, 28 Sep 2020 12:04:05 -0700 (PDT)", "from qc2400f-1.austin.arm.com (qc2400f-1.austin.arm.com\n [10.118.12.27])\n by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 355963F70D;\n Mon, 28 Sep 2020 12:04:05 -0700 (PDT)" ], "From": "Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>", "To": "dev@dpdk.org, honnappa.nagarahalli@arm.com, phil.yang@arm.com,\n jgrajcia@cisco.com, ferruh.yigit@intel.com", "Cc": "nd@arm.com,\n\tstable@dpdk.org", "Date": "Mon, 28 Sep 2020 14:03:28 -0500", "Message-Id": "<20200928190334.40624-2-honnappa.nagarahalli@arm.com>", "X-Mailer": "git-send-email 2.17.1", "In-Reply-To": "<20200928190334.40624-1-honnappa.nagarahalli@arm.com>", "References": "<20200921192254.20560-1-honnappa.nagarahalli@arm.com>\n <20200928190334.40624-1-honnappa.nagarahalli@arm.com>", "Subject": "[dpdk-dev] [PATCH v2 2/8] net/memif: relax the load of ring tail\n\tpointer for M2S ring", "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": "For M2S rings, ring->tail is updated by the sender and eth_memif_tx\nfunction is called in the context of sending thread. The loads in\nthe sender do not need to synchronize with its own stores.\n\nFixes: a2aafb9aa651 (\"net/memif: optimize with one-way barrier\")\nCc: phil.yang@arm.com\nCc: stable@dpdk.org\n\nSigned-off-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>\nReviewed-by: Phil Yang <phil.yang@arm.com>\nReviewed-by: Ruifeng Wang <ruifeng.wang@arm.com>\n---\n drivers/net/memif/rte_eth_memif.c | 8 +++++++-\n 1 file changed, 7 insertions(+), 1 deletion(-)", "diff": "diff --git a/drivers/net/memif/rte_eth_memif.c b/drivers/net/memif/rte_eth_memif.c\nindex 130099f2e..8bacacaa8 100644\n--- a/drivers/net/memif/rte_eth_memif.c\n+++ b/drivers/net/memif/rte_eth_memif.c\n@@ -585,7 +585,13 @@ eth_memif_tx(void *queue, struct rte_mbuf **bufs, uint16_t nb_pkts)\n \t\tn_free = ring_size - slot +\n \t\t\t\t__atomic_load_n(&ring->tail, __ATOMIC_ACQUIRE);\n \t} else {\n-\t\tslot = __atomic_load_n(&ring->tail, __ATOMIC_ACQUIRE);\n+\t\t/* For M2S queues ring->tail is updated by the sender and\n+\t\t * this function is called in the context of sending thread.\n+\t\t * The loads in the sender do not need to synchronize with\n+\t\t * its own stores. Hence, the following load can be a\n+\t\t * relaxed load.\n+\t\t */\n+\t\tslot = __atomic_load_n(&ring->tail, __ATOMIC_RELAXED);\n \t\tn_free = __atomic_load_n(&ring->head, __ATOMIC_ACQUIRE) - slot;\n \t}\n \n", "prefixes": [ "v2", "2/8" ] }