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GET /api/patches/633391/?format=api
HTTP 200 OK
Allow: GET, PUT, PATCH, HEAD, OPTIONS
Content-Type: application/json
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{
    "id": 633391,
    "url": "http://patchwork.ozlabs.org/api/patches/633391/?format=api",
    "web_url": "http://patchwork.ozlabs.org/project/intel-wired-lan/patch/20160609215605.19957-1-jacob.e.keller@intel.com/",
    "project": {
        "id": 46,
        "url": "http://patchwork.ozlabs.org/api/projects/46/?format=api",
        "name": "Intel Wired Ethernet development",
        "link_name": "intel-wired-lan",
        "list_id": "intel-wired-lan.osuosl.org",
        "list_email": "intel-wired-lan@osuosl.org",
        "web_url": "",
        "scm_url": "",
        "webscm_url": "",
        "list_archive_url": "",
        "list_archive_url_format": "",
        "commit_url_format": ""
    },
    "msgid": "<20160609215605.19957-1-jacob.e.keller@intel.com>",
    "list_archive_url": null,
    "date": "2016-06-09T21:56:05",
    "name": "[v2] fm10k: use software values when checking for Tx hangs in hot path",
    "commit_ref": null,
    "pull_url": null,
    "state": "accepted",
    "archived": false,
    "hash": "9096e14f96b581eb7345031ab1f0cf7a417b776e",
    "submitter": {
        "id": 9784,
        "url": "http://patchwork.ozlabs.org/api/people/9784/?format=api",
        "name": "Jacob Keller",
        "email": "jacob.e.keller@intel.com"
    },
    "delegate": {
        "id": 68,
        "url": "http://patchwork.ozlabs.org/api/users/68/?format=api",
        "username": "jtkirshe",
        "first_name": "Jeff",
        "last_name": "Kirsher",
        "email": "jeffrey.t.kirsher@intel.com"
    },
    "mbox": "http://patchwork.ozlabs.org/project/intel-wired-lan/patch/20160609215605.19957-1-jacob.e.keller@intel.com/mbox/",
    "series": [],
    "comments": "http://patchwork.ozlabs.org/api/patches/633391/comments/",
    "check": "pending",
    "checks": "http://patchwork.ozlabs.org/api/patches/633391/checks/",
    "tags": {},
    "related": [],
    "headers": {
        "Return-Path": "<intel-wired-lan-bounces@lists.osuosl.org>",
        "X-Original-To": [
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        "Delivered-To": [
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            "intel-wired-lan@lists.osuosl.org"
        ],
        "Received": [
            "from hemlock.osuosl.org (smtp2.osuosl.org [140.211.166.133])\n\t(using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits))\n\t(No client certificate requested)\n\tby ozlabs.org (Postfix) with ESMTPS id 3rQfJW5D73z9sBG\n\tfor <incoming@patchwork.ozlabs.org>;\n\tFri, 10 Jun 2016 07:56:11 +1000 (AEST)",
            "from localhost (localhost [127.0.0.1])\n\tby hemlock.osuosl.org (Postfix) with ESMTP id 468F3956B4;\n\tThu,  9 Jun 2016 21:56:10 +0000 (UTC)",
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            "from localhost (localhost [127.0.0.1])\n\tby silver.osuosl.org (Postfix) with ESMTP id 7B7FE3097F\n\tfor <intel-wired-lan@lists.osuosl.org>;\n\tThu,  9 Jun 2016 21:56:08 +0000 (UTC)",
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            "from fmsmga002.fm.intel.com ([10.253.24.26])\n\tby fmsmga102.fm.intel.com with ESMTP; 09 Jun 2016 14:56:08 -0700",
            "from jekeller-desk.amr.corp.intel.com (HELO\n\tjekeller-desk.jekeller.internal) ([134.134.3.116])\n\tby fmsmga002.fm.intel.com with ESMTP; 09 Jun 2016 14:56:06 -0700"
        ],
        "X-Virus-Scanned": [
            "amavisd-new at osuosl.org",
            "amavisd-new at osuosl.org"
        ],
        "X-Greylist": "domain auto-whitelisted by SQLgrey-1.7.6",
        "X-ExtLoop1": "1",
        "X-IronPort-AV": "E=Sophos;i=\"5.26,447,1459839600\"; d=\"scan'208\";a=\"998868522\"",
        "From": "Jacob Keller <jacob.e.keller@intel.com>",
        "To": "Intel Wired LAN <intel-wired-lan@lists.osuosl.org>",
        "Date": "Thu,  9 Jun 2016 14:56:05 -0700",
        "Message-Id": "<20160609215605.19957-1-jacob.e.keller@intel.com>",
        "X-Mailer": "git-send-email 2.9.0.rc1.405.g81f467e",
        "Subject": "[Intel-wired-lan] [PATCH v2] fm10k: use software values when\n\tchecking for Tx hangs in hot path",
        "X-BeenThere": "intel-wired-lan@lists.osuosl.org",
        "X-Mailman-Version": "2.1.18-1",
        "Precedence": "list",
        "List-Id": "Intel Wired Ethernet Linux Kernel Driver Development\n\t<intel-wired-lan.lists.osuosl.org>",
        "List-Unsubscribe": "<http://lists.osuosl.org/mailman/options/intel-wired-lan>, \n\t<mailto:intel-wired-lan-request@lists.osuosl.org?subject=unsubscribe>",
        "List-Archive": "<http://lists.osuosl.org/pipermail/intel-wired-lan/>",
        "List-Post": "<mailto:intel-wired-lan@lists.osuosl.org>",
        "List-Help": "<mailto:intel-wired-lan-request@lists.osuosl.org?subject=help>",
        "List-Subscribe": "<http://lists.osuosl.org/mailman/listinfo/intel-wired-lan>, \n\t<mailto:intel-wired-lan-request@lists.osuosl.org?subject=subscribe>",
        "MIME-Version": "1.0",
        "Content-Type": "text/plain; charset=\"us-ascii\"",
        "Content-Transfer-Encoding": "7bit",
        "Errors-To": "intel-wired-lan-bounces@lists.osuosl.org",
        "Sender": "\"Intel-wired-lan\" <intel-wired-lan-bounces@lists.osuosl.org>"
    },
    "content": "A previous patch added support to check for hardware tx pending in the\nfm10k_down routine. This support was intended to ensure that we\naccurately check what the hardware state is. However, checking for Tx\nhangs in this manor during the hotpath results in a large performance\nhit. Avoid this by making the hotpath check use the SW counters instead.\n\nFixes: a0f53cf49cb0 (\"fm10k: use actual hardware registers when checking for pending Tx\", 2016-06-08)\nSigned-off-by: Jacob Keller <jacob.e.keller@intel.com>\n---\n drivers/net/ethernet/intel/fm10k/fm10k.h      |  2 +-\n drivers/net/ethernet/intel/fm10k/fm10k_main.c | 19 +++++++++++++++----\n drivers/net/ethernet/intel/fm10k/fm10k_pci.c  |  2 +-\n 3 files changed, 17 insertions(+), 6 deletions(-)",
    "diff": "diff --git a/drivers/net/ethernet/intel/fm10k/fm10k.h b/drivers/net/ethernet/intel/fm10k/fm10k.h\nindex c4cf08dcf5af..75429f2bbc97 100644\n--- a/drivers/net/ethernet/intel/fm10k/fm10k.h\n+++ b/drivers/net/ethernet/intel/fm10k/fm10k.h\n@@ -458,7 +458,7 @@ __be16 fm10k_tx_encap_offload(struct sk_buff *skb);\n netdev_tx_t fm10k_xmit_frame_ring(struct sk_buff *skb,\n \t\t\t\t  struct fm10k_ring *tx_ring);\n void fm10k_tx_timeout_reset(struct fm10k_intfc *interface);\n-u64 fm10k_get_tx_pending(struct fm10k_ring *ring);\n+u64 fm10k_get_tx_pending(struct fm10k_ring *ring, bool in_sw);\n bool fm10k_check_tx_hang(struct fm10k_ring *tx_ring);\n void fm10k_alloc_rx_buffers(struct fm10k_ring *rx_ring, u16 cleaned_count);\n \ndiff --git a/drivers/net/ethernet/intel/fm10k/fm10k_main.c b/drivers/net/ethernet/intel/fm10k/fm10k_main.c\nindex e9767b6366a8..a4ea84273ea1 100644\n--- a/drivers/net/ethernet/intel/fm10k/fm10k_main.c\n+++ b/drivers/net/ethernet/intel/fm10k/fm10k_main.c\n@@ -1128,13 +1128,24 @@ static u64 fm10k_get_tx_completed(struct fm10k_ring *ring)\n \treturn ring->stats.packets;\n }\n \n-u64 fm10k_get_tx_pending(struct fm10k_ring *ring)\n+/**\n+ * fm10k_get_tx_pending - how many tx descriptors not processed\n+ * @ring: the ring structure\n+ * @in_sw: is tx_pending being checked in SW or in HW?\n+ */\n+u64 fm10k_get_tx_pending(struct fm10k_ring *ring, bool in_sw)\n {\n \tstruct fm10k_intfc *interface = ring->q_vector->interface;\n \tstruct fm10k_hw *hw = &interface->hw;\n+\tu32 head, tail;\n \n-\tu32 head = fm10k_read_reg(hw, FM10K_TDH(ring->reg_idx));\n-\tu32 tail = fm10k_read_reg(hw, FM10K_TDT(ring->reg_idx));\n+\tif (likely(in_sw)) {\n+\t\thead = ring->next_to_clean;\n+\t\ttail = ring->next_to_use;\n+\t} else {\n+\t\thead = fm10k_read_reg(hw, FM10K_TDH(ring->reg_idx));\n+\t\ttail = fm10k_read_reg(hw, FM10K_TDT(ring->reg_idx));\n+\t}\n \n \treturn ((head <= tail) ? tail : tail + ring->count) - head;\n }\n@@ -1143,7 +1154,7 @@ bool fm10k_check_tx_hang(struct fm10k_ring *tx_ring)\n {\n \tu32 tx_done = fm10k_get_tx_completed(tx_ring);\n \tu32 tx_done_old = tx_ring->tx_stats.tx_done_old;\n-\tu32 tx_pending = fm10k_get_tx_pending(tx_ring);\n+\tu32 tx_pending = fm10k_get_tx_pending(tx_ring, true);\n \n \tclear_check_for_tx_hang(tx_ring);\n \ndiff --git a/drivers/net/ethernet/intel/fm10k/fm10k_pci.c b/drivers/net/ethernet/intel/fm10k/fm10k_pci.c\nindex 559cda999f49..b0c3d7b3a34c 100644\n--- a/drivers/net/ethernet/intel/fm10k/fm10k_pci.c\n+++ b/drivers/net/ethernet/intel/fm10k/fm10k_pci.c\n@@ -1699,7 +1699,7 @@ void fm10k_down(struct fm10k_intfc *interface)\n \n \t\t/* start checking at the last ring to have pending Tx */\n \t\tfor (; i < interface->num_tx_queues; i++)\n-\t\t\tif (fm10k_get_tx_pending(interface->tx_ring[i]))\n+\t\t\tif (fm10k_get_tx_pending(interface->tx_ring[i], false))\n \t\t\t\tbreak;\n \n \t\t/* if all the queues are drained, we can break now */\n",
    "prefixes": [
        "v2"
    ]
}