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GET /api/patches/10436/?format=api
{ "id": 10436, "url": "http://patches.dpdk.org/api/patches/10436/?format=api", "web_url": "http://patches.dpdk.org/project/dpdk/patch/1454946137-5505-1-git-send-email-harry.van.haaren@intel.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": "<1454946137-5505-1-git-send-email-harry.van.haaren@intel.com>", "list_archive_url": "https://inbox.dpdk.org/dev/1454946137-5505-1-git-send-email-harry.van.haaren@intel.com", "date": "2016-02-08T15:42:17", "name": "[dpdk-dev] docs: add statistics read frequency to fm10k guide", "commit_ref": null, "pull_url": null, "state": "superseded", "archived": true, "hash": "d7e589a290ce697cfab6834e7c170e730628e2ee", "submitter": { "id": 317, "url": "http://patches.dpdk.org/api/people/317/?format=api", "name": "Van Haaren, Harry", "email": "harry.van.haaren@intel.com" }, "delegate": null, "mbox": "http://patches.dpdk.org/project/dpdk/patch/1454946137-5505-1-git-send-email-harry.van.haaren@intel.com/mbox/", "series": [], "comments": "http://patches.dpdk.org/api/patches/10436/comments/", "check": "pending", "checks": "http://patches.dpdk.org/api/patches/10436/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 [IPv6:::1])\n\tby dpdk.org (Postfix) with ESMTP id E03BC58C3;\n\tMon, 8 Feb 2016 16:42:32 +0100 (CET)", "from mga14.intel.com (mga14.intel.com [192.55.52.115])\n\tby dpdk.org (Postfix) with ESMTP id 163DD559C\n\tfor <dev@dpdk.org>; Mon, 8 Feb 2016 16:42:30 +0100 (CET)", "from orsmga003.jf.intel.com ([10.7.209.27])\n\tby fmsmga103.fm.intel.com with ESMTP; 08 Feb 2016 07:42:30 -0800", "from sie-lab-212-120.ir.intel.com (HELO\n\tsilpixa00394367.ir.intel.com) ([10.237.212.120])\n\tby orsmga003.jf.intel.com with ESMTP; 08 Feb 2016 07:42:28 -0800" ], "X-ExtLoop1": "1", "X-IronPort-AV": "E=Sophos;i=\"5.22,416,1449561600\"; d=\"scan'208\";a=\"742490610\"", "From": "Harry van Haaren <harry.van.haaren@intel.com>", "To": "jing.d.chen@intel.com", "Date": "Mon, 8 Feb 2016 15:42:17 +0000", "Message-Id": "<1454946137-5505-1-git-send-email-harry.van.haaren@intel.com>", "X-Mailer": "git-send-email 2.5.0", "Cc": "dev@dpdk.org", "Subject": "[dpdk-dev] [PATCH] docs: add statistics read frequency to fm10k\n\tguide", "X-BeenThere": "dev@dpdk.org", "X-Mailman-Version": "2.1.15", "Precedence": "list", "List-Id": "patches and discussions about DPDK <dev.dpdk.org>", "List-Unsubscribe": "<http://dpdk.org/ml/options/dev>,\n\t<mailto:dev-request@dpdk.org?subject=unsubscribe>", "List-Archive": "<http://dpdk.org/ml/archives/dev/>", "List-Post": "<mailto:dev@dpdk.org>", "List-Help": "<mailto:dev-request@dpdk.org?subject=help>", "List-Subscribe": "<http://dpdk.org/ml/listinfo/dev>,\n\t<mailto:dev-request@dpdk.org?subject=subscribe>", "Errors-To": "dev-bounces@dpdk.org", "Sender": "\"dev\" <dev-bounces@dpdk.org>" }, "content": "This patch documents that the statistics of fm10k based NICs must be\nread regularly in order to avoid an undetected 32 bit integer-overflow.\n\nSigned-off-by: Harry van Haaren <harry.van.haaren@intel.com>\n---\n doc/guides/nics/fm10k.rst | 16 ++++++++++++++++\n doc/guides/rel_notes/release_2_3.rst | 4 ++++\n 2 files changed, 20 insertions(+)", "diff": "diff --git a/doc/guides/nics/fm10k.rst b/doc/guides/nics/fm10k.rst\nindex 4206b7f..4250c9e 100644\n--- a/doc/guides/nics/fm10k.rst\n+++ b/doc/guides/nics/fm10k.rst\n@@ -65,3 +65,19 @@ The FM10000 family of NICS support a maximum of a 15K jumbo frame. The value\n is fixed and cannot be changed. So, even when the ``rxmode.max_rx_pkt_len``\n member of ``struct rte_eth_conf`` is set to a value lower than 15364, frames\n up to 15364 bytes can still reach the host interface.\n+\n+Statistic Polling Frequency\n+~~~~~~~~~~~~~~~~~~~~~~~~~~~\n+\n+The FM10000 NICs expose a set of statistics via the PCI BARs. These statistics\n+are read from the hardware registers when ``rte_eth_stats_get()`` or\n+``rte_eth_xstats_get()`` is called. The packet counting registers are 32 bits\n+while the byte counting registers are 48 bits. As a result, the statistics must\n+be polled regularly in order to ensure the consistency of the returned reads.\n+\n+Given the PCIe Gen3 x8, about 50Gbps of traffic can occur. With 64 byte packets\n+this gives almost 100 million packets/second, causing 32 bit integer overflow\n+after approx 40 seconds. To ensure these overflows are detected and accounted\n+for in the statistics, it is necessary to read statistic regularly. It is\n+suggested to read stats every 20 seconds, which will gaurantee the statistics\n+are accurate.\ndiff --git a/doc/guides/rel_notes/release_2_3.rst b/doc/guides/rel_notes/release_2_3.rst\nindex 99de186..f966940 100644\n--- a/doc/guides/rel_notes/release_2_3.rst\n+++ b/doc/guides/rel_notes/release_2_3.rst\n@@ -15,6 +15,10 @@ EAL\n Drivers\n ~~~~~~~\n \n+* **FM10K: Statistics Polling Frequency**\n+\n+ A section has been added to the NIC guide for fm10k about the time\n+ between reading statistics and 32 bit packet counter overflows.\n \n Libraries\n ~~~~~~~~~\n", "prefixes": [ "dpdk-dev" ] }