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{
    "id": 142,
    "url": "https://patches.dpdk.org/api/patches/142/?format=api",
    "web_url": "https://patches.dpdk.org/patch/142/",
    "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"
    },
    "msgid": "<1407789890-17355-7-git-send-email-bruce.richardson@intel.com>",
    "date": "2014-08-11T20:44:42",
    "name": "[dpdk-dev,RFC,06/14] mbuf: reorder fields by time-of-use",
    "commit_ref": "",
    "pull_url": "",
    "state": "rfc",
    "archived": true,
    "hash": "47173ebe47010e545ddcf9d3fa1a7f6516bca0b2",
    "submitter": {
        "id": 20,
        "url": "https://patches.dpdk.org/api/people/20/?format=api",
        "name": "Bruce Richardson",
        "email": "bruce.richardson@intel.com"
    },
    "delegate": null,
    "mbox": "https://patches.dpdk.org/patch/142/mbox/",
    "series": [],
    "comments": "https://patches.dpdk.org/api/patches/142/comments/",
    "check": "pending",
    "checks": "https://patches.dpdk.org/api/patches/142/checks/",
    "tags": {},
    "headers": {
        "List-Archive": "<http://dpdk.org/ml/archives/dev/>",
        "Return-Path": "<bricha3@ecsmtp.ir.intel.com>",
        "Message-Id": "<1407789890-17355-7-git-send-email-bruce.richardson@intel.com>",
        "X-Mailer": "git-send-email 1.7.0.7",
        "To": "dev@dpdk.org",
        "List-Subscribe": "<http://dpdk.org/ml/listinfo/dev>,\r\n\t<mailto:dev-request@dpdk.org?subject=subscribe>",
        "X-BeenThere": "dev@dpdk.org",
        "Received": [
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            "from sivswdev02.ir.intel.com (sivswdev02.ir.intel.com\r\n\t[10.237.217.46])\r\n\tby irvmail001.ir.intel.com (8.14.3/8.13.6/MailSET/Hub) with ESMTP id\r\n\ts7BKiqmE020951; Mon, 11 Aug 2014 21:44:52 +0100",
            "from sivswdev02.ir.intel.com (localhost [127.0.0.1])\r\n\tby sivswdev02.ir.intel.com with ESMTP id s7BKiq4X017681;\r\n\tMon, 11 Aug 2014 21:44:52 +0100",
            "(from bricha3@localhost)\r\n\tby sivswdev02.ir.intel.com with  id s7BKiqnB017677;\r\n\tMon, 11 Aug 2014 21:44:52 +0100"
        ],
        "Subject": "[dpdk-dev] [RFC PATCH 06/14] mbuf: reorder fields by time-of-use",
        "List-Unsubscribe": "<http://dpdk.org/ml/options/dev>,\r\n\t<mailto:dev-request@dpdk.org?subject=unsubscribe>",
        "List-Id": "patches and discussions about DPDK <dev.dpdk.org>",
        "List-Post": "<mailto:dev@dpdk.org>",
        "In-Reply-To": "<1407789890-17355-1-git-send-email-bruce.richardson@intel.com>",
        "X-ExtLoop1": "1",
        "Precedence": "list",
        "From": "Bruce Richardson <bruce.richardson@intel.com>",
        "X-IronPort-AV": "E=Sophos;i=\"5.01,844,1400050800\"; d=\"scan'208\";a=\"586659689\"",
        "References": "<1407789890-17355-1-git-send-email-bruce.richardson@intel.com>",
        "X-List-Received-Date": "Mon, 11 Aug 2014 20:44:07 -0000",
        "List-Help": "<mailto:dev-request@dpdk.org?subject=help>",
        "Date": "Mon, 11 Aug 2014 21:44:42 +0100",
        "X-Mailman-Version": "2.1.15"
    },
    "content": "*  Reorder the fields in the mbuf so that we have fields that are used\ntogether side-by-side in the structure. This means that we have a\ncontiguous block of 8-bytes in the mbuf which are used to reset an mbuf\nof descriptor rearm.\n*  Where needed add in a dummy fields to overwrite values 8 or 16 bytes\nat a time, when doing RX or RX descriptor rearm. This avoids compiler\nwarnings when using uint64_t values to overwrite a set of smaller\nvalues.\n* At the end, place fields that are only used for TX or for the slower\nRX path, and mark them as down to be moved to a second cache line.\n\nSigned-off-by: Bruce Richardson <bruce.richardson@intel.com>\n---\n lib/librte_mbuf/rte_mbuf.c |  2 +-\n lib/librte_mbuf/rte_mbuf.h | 37 +++++++++++++++++++++----------------\n 2 files changed, 22 insertions(+), 17 deletions(-)",
    "diff": "diff --git a/lib/librte_mbuf/rte_mbuf.c b/lib/librte_mbuf/rte_mbuf.c\r\nindex 64f1587..594b910 100644\r\n--- a/lib/librte_mbuf/rte_mbuf.c\r\n+++ b/lib/librte_mbuf/rte_mbuf.c\r\n@@ -161,7 +161,7 @@ rte_pktmbuf_dump(FILE *f, const struct rte_mbuf *m, unsigned dump_len)\r\n \r\n \tfprintf(f, \"dump mbuf at 0x%p, phys=%\"PRIx64\", buf_len=%u\\n\",\r\n \t       m, (uint64_t)m->buf_physaddr, (unsigned)m->buf_len);\r\n-\tfprintf(f, \"  pkt_len=%\"PRIu32\", ol_flags=%\"PRIx16\", nb_segs=%u, \"\r\n+\tfprintf(f, \"  pkt_len=%\"PRIu32\", ol_flags=%\"PRIx64\", nb_segs=%u, \"\r\n \t       \"in_port=%u\\n\", m->pkt_len, m->ol_flags,\r\n \t       (unsigned)m->nb_segs, (unsigned)m->port);\r\n \tnb_segs = m->nb_segs;\r\ndiff --git a/lib/librte_mbuf/rte_mbuf.h b/lib/librte_mbuf/rte_mbuf.h\r\nindex e0981c9..566bb7e 100644\r\n--- a/lib/librte_mbuf/rte_mbuf.h\r\n+++ b/lib/librte_mbuf/rte_mbuf.h\r\n@@ -132,22 +132,20 @@ union rte_vlan_macip {\r\n /**< MAC+IP  length. */\r\n #define TX_MACIP_LEN_CMP_MASK   (TX_MAC_LEN_CMP_MASK | TX_IP_LEN_CMP_MASK)\r\n \r\n+\r\n /**\r\n  * The generic rte_mbuf, containing a packet mbuf.\r\n  */\r\n struct rte_mbuf {\r\n-\tstruct rte_mempool *pool; /**< Pool from which mbuf was allocated. */\r\n \tvoid *buf_addr;           /**< Virtual address of segment buffer. */\r\n \tphys_addr_t buf_physaddr; /**< Physical address of segment buffer. */\r\n-\tuint16_t buf_len;         /**< Length of segment buffer. */\r\n \r\n-\t/* valid for any segment */\r\n-\tstruct rte_mbuf *next;    /**< Next segment of scattered packet. */\r\n+\t/* next 8 bytes are initialised on RX descriptor rearm */\r\n+\tuint64_t rearm_data[0]; /**< dummy element so we can get uin64_t ptrs\r\n+\t                         * to this part of the mbuf without alias error\r\n+\t                         */\r\n+\tuint16_t buf_len;       /**< Length of segment buffer. */\r\n \tuint16_t data_off;\r\n-\tuint16_t data_len;        /**< Amount of data in segment buffer. */\r\n-\tuint32_t pkt_len;         /**< Total pkt len: sum of all segments. */\r\n-\r\n-#ifdef RTE_MBUF_REFCNT\r\n \t/**\r\n \t * 16-bit Reference counter.\r\n \t * It should only be accessed using the following functions:\r\n@@ -157,20 +155,23 @@ struct rte_mbuf {\r\n \t * config option.\r\n \t */\r\n \tunion {\r\n+#ifdef RTE_MBUF_REFCNT\r\n \t\trte_atomic16_t refcnt_atomic;   /**< Atomically accessed refcnt */\r\n \t\tuint16_t refcnt;                /**< Non-atomically accessed refcnt */\r\n-\t};\r\n-#else\r\n-\tuint16_t refcnt_reserved;     /**< Do not use this field */\r\n #endif\r\n-\r\n-\t/* these fields are valid for first segment only */\r\n+\t\tuint16_t refcnt_reserved;     /**< Do not use this field */\r\n+\t};\r\n \tuint8_t nb_segs;        /**< Number of segments. */\r\n \tuint8_t port;        /**< Input port. */\r\n-\tuint16_t ol_flags;            /**< Offload features. */\r\n-\tuint16_t reserved;             /**< Unused field. Required for padding. */\r\n \r\n-\t/* offload features, valid for first segment only */\r\n+\t/* remaining bytes are set on RX when pulling packet from descriptor */\r\n+\tuint64_t ol_flags;        /**< Offload features. */\r\n+\r\n+\t__m128i rx_descriptor_fields1[0]; /**< dummy field used as marker for\r\n+\t                                   * writes in a vector driver */\r\n+\tuint16_t packet_type;     /**< Type of packet, e.g. protocols used */\r\n+\tuint16_t data_len;        /**< Amount of data in segment buffer. */\r\n+\tuint32_t pkt_len;         /**< Total pkt len: sum of all segments. */\r\n \tunion rte_vlan_macip vlan_macip;\r\n \tunion {\r\n \t\tuint32_t rss;       /**< RSS hash result if RSS enabled */\r\n@@ -181,6 +182,10 @@ struct rte_mbuf {\r\n \t\tuint32_t sched;     /**< Hierarchical scheduler */\r\n \t} hash;                 /**< hash information */\r\n \r\n+\t/* second cache line, fields only used in slow path or on TX */\r\n+\tstruct rte_mempool *pool; /**< Pool from which mbuf was allocated. */\r\n+\tstruct rte_mbuf *next;    /**< Next segment of scattered packet. */\r\n+\r\n \tunion {\r\n \t\tuint8_t metadata[0];\r\n \t\tuint16_t metadata16[0];\r\n",
    "prefixes": [
        "dpdk-dev",
        "RFC",
        "06/14"
    ]
}