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Tue, 4 Mar 2025 19:05:50 +0000 Received: from EX19MTAUEC001.ant.amazon.com (10.252.135.222) by EX19D008UEA001.ant.amazon.com (10.252.134.62) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA) id 15.2.1544.14; Tue, 4 Mar 2025 19:05:50 +0000 Received: from email-imr-corp-prod-iad-all-1a-93a35fb4.us-east-1.amazon.com (10.43.8.6) by mail-relay.amazon.com (10.252.135.200) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA) id 15.2.1544.14 via Frontend Transport; Tue, 4 Mar 2025 19:05:50 +0000 Received: from HFA15-G9FV5D3.amazon.com (unknown [10.85.143.178]) by email-imr-corp-prod-iad-all-1a-93a35fb4.us-east-1.amazon.com (Postfix) with ESMTP id 705F740477; Tue, 4 Mar 2025 19:05:45 +0000 (UTC) From: David Arinzon To: David Miller , Jakub Kicinski , CC: David Arinzon , Eric Dumazet , Paolo Abeni , Simon Horman , "Richard Cochran" , "Woodhouse, David" , "Machulsky, Zorik" , "Matushevsky, Alexander" , Saeed Bshara , "Wilson, Matt" , "Liguori, Anthony" , "Bshara, Nafea" , "Schmeilin, Evgeny" , "Belgazal, Netanel" , "Saidi, Ali" , "Herrenschmidt, Benjamin" , "Kiyanovski, Arthur" , "Dagan, Noam" , "Bernstein, Amit" , "Agroskin, Shay" , "Ostrovsky, Evgeny" , "Tabachnik, Ofir" , "Machnikowski, Maciek" , Rahul Rameshbabu , Gal Pressman , Vadim Fedorenko Subject: [PATCH v8 net-next 5/5] net: ena: Add PHC documentation Date: Tue, 4 Mar 2025 21:05:04 +0200 Message-ID: <20250304190504.3743-6-darinzon@amazon.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20250304190504.3743-1-darinzon@amazon.com> References: <20250304190504.3743-1-darinzon@amazon.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Patchwork-Delegate: kuba@kernel.org Provide the relevant information and guidelines about the feature support in the ENA driver. Signed-off-by: Amit Bernstein Signed-off-by: David Arinzon --- .../device_drivers/ethernet/amazon/ena.rst | 96 +++++++++++++++++++ 1 file changed, 96 insertions(+) diff --git a/Documentation/networking/device_drivers/ethernet/amazon/ena.rst b/Documentation/networking/device_drivers/ethernet/amazon/ena.rst index 4561e8ab..158d7100 100644 --- a/Documentation/networking/device_drivers/ethernet/amazon/ena.rst +++ b/Documentation/networking/device_drivers/ethernet/amazon/ena.rst @@ -53,9 +53,11 @@ ena_eth_io_defs.h Definition of ENA data path interface. ena_common_defs.h Common definitions for ena_com layer. ena_regs_defs.h Definition of ENA PCI memory-mapped (MMIO) registers. ena_netdev.[ch] Main Linux kernel driver. +ena_sysfs.[ch] Sysfs files. ena_ethtool.c ethtool callbacks. ena_xdp.[ch] XDP files ena_pci_id_tbl.h Supported device IDs. +ena_phc.[ch] PTP hardware clock infrastructure (see `PHC`_ for more info) ================= ====================================================== Management Interface: @@ -221,6 +223,100 @@ descriptor it was received on would be recycled. When a packet smaller than RX copybreak bytes is received, it is copied into a new memory buffer and the RX descriptor is returned to HW. +.. _`PHC`: + +PTP Hardware Clock (PHC) +======================== +.. _`ptp-userspace-api`: https://docs.kernel.org/driver-api/ptp.html#ptp-hardware-clock-user-space-api +.. _`testptp`: https://elixir.bootlin.com/linux/latest/source/tools/testing/selftests/ptp/testptp.c + +ENA Linux driver supports PTP hardware clock providing timestamp reference to achieve nanosecond resolution. + +**PHC support** + +PHC depends on the PTP module, which needs to be either loaded as a module or compiled into the kernel. + +Verify if the PTP module is present: + +.. code-block:: shell + + grep -w '^CONFIG_PTP_1588_CLOCK=[ym]' /boot/config-`uname -r` + +- If no output is provided, the ENA driver cannot be loaded with PHC support. + +- ``CONFIG_PTP_1588_CLOCK=y``: the PTP module is already compiled and loaded inside the kernel binary file. + +- ``CONFIG_PTP_1588_CLOCK=m``: the PTP module needs to be loaded prior to loading the ENA driver: + +Load PTP module: + +.. code-block:: shell + + sudo modprobe ptp + +**PHC activation** + +The feature is turned off by default, in order to turn the feature on, +please use the following: + +- sysfs (during runtime): + +.. code-block:: shell + + echo 1 > /sys/bus/pci/devices//phc_enable + +All available PTP clock sources can be tracked here: + +.. code-block:: shell + + ls /sys/class/ptp + +PHC support and capabilities can be verified using ethtool: + +.. code-block:: shell + + ethtool -T + +**PHC timestamp** + +To retrieve PHC timestamp, use `ptp-userspace-api`_, usage example using `testptp`_: + +.. code-block:: shell + + testptp -d /dev/ptp$(ethtool -T | awk '/PTP Hardware Clock:/ {print $NF}') -k 1 + +PHC get time requests should be within reasonable bounds, +avoid excessive utilization to ensure optimal performance and efficiency. +The ENA device restricts the frequency of PHC get time requests to a maximum +of 125 requests per second. If this limit is surpassed, the get time request +will fail, leading to an increment in the phc_err statistic. + +**PHC statistics** + +PHC counters can be monitored using the following: + +sysfs: + +.. code-block:: shell + + cat /sys/bus/pci/devices//phc_stats/ + +================= ====================================================== +**phc_cnt** Number of successful retrieved timestamps (below expire timeout). +**phc_exp** Number of expired retrieved timestamps (above expire timeout). +**phc_skp** Number of skipped get time attempts (during block period). +**phc_err** Number of failed get time attempts (entering into block state). +================= ====================================================== + +PHC timeouts: + +================= ====================================================== +**expire** Max time for a valid timestamp retrieval, passing this threshold will fail + the get time request and block new requests until block timeout. +**block** Blocking period starts once get time request expires or fails, all get time + requests during block period will be skipped. +================= ====================================================== + Statistics ==========