From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from dpdk.org (dpdk.org [92.243.14.124]) by inbox.dpdk.org (Postfix) with ESMTP id B4F7DA00C5; Mon, 6 Jul 2020 19:19:24 +0200 (CEST) Received: from [92.243.14.124] (localhost [127.0.0.1]) by dpdk.org (Postfix) with ESMTP id 8AD591D698; Mon, 6 Jul 2020 19:19:24 +0200 (CEST) Received: from mga02.intel.com (mga02.intel.com [134.134.136.20]) by dpdk.org (Postfix) with ESMTP id 648BB1C43E; Mon, 6 Jul 2020 19:19:22 +0200 (CEST) IronPort-SDR: VElsqBKGxaUjcga37q46Oxr2fpaJADRGeXUZdDsglV53qufCbRasZIYJwU/5dgWx/sK7rbyZV0 O8oWOuRCEYSQ== X-IronPort-AV: E=McAfee;i="6000,8403,9673"; a="135709262" X-IronPort-AV: E=Sophos;i="5.75,320,1589266800"; d="scan'208";a="135709262" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga004.fm.intel.com ([10.253.24.48]) by orsmga101.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 06 Jul 2020 10:19:21 -0700 IronPort-SDR: IF0Z0UiCN/8pDM8ISykTCDGDjkoGr9ZiL7c8I+qHK0Sn7HbXhSuIV5cmPZS+iN4XcdgqRTI6wp Vzqug+jDNQMQ== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.75,320,1589266800"; d="scan'208";a="305367878" Received: from fyigit-mobl.ger.corp.intel.com (HELO [10.252.18.158]) ([10.252.18.158]) by fmsmga004.fm.intel.com with ESMTP; 06 Jul 2020 10:19:18 -0700 To: Honnappa Nagarahalli , "dev@dpdk.org" , "alialnu@mellanox.com" , "orgerlitz@mellanox.com" , "wenzhuo.lu@intel.com" , "beilei.xing@intel.com" , "bernard.iremonger@intel.com" Cc: "hemant.agrawal@nxp.com" , "jerinj@marvell.com" , "viacheslavo@mellanox.com" , "thomas@monjalon.net" , Ruifeng Wang , Phil Yang , nd , "zhihong.wang@intel.com" , "stable@dpdk.org" References: <20200617144307.9961-1-honnappa.nagarahalli@arm.com> <20200626220943.22526-1-honnappa.nagarahalli@arm.com> <6dd1c866-8e41-4952-9792-b1fd492d0908@intel.com> From: Ferruh Yigit Autocrypt: addr=ferruh.yigit@intel.com; prefer-encrypt=mutual; keydata= mQINBFXZCFABEADCujshBOAaqPZpwShdkzkyGpJ15lmxiSr3jVMqOtQS/sB3FYLT0/d3+bvy qbL9YnlbPyRvZfnP3pXiKwkRoR1RJwEo2BOf6hxdzTmLRtGtwWzI9MwrUPj6n/ldiD58VAGQ +iR1I/z9UBUN/ZMksElA2D7Jgg7vZ78iKwNnd+vLBD6I61kVrZ45Vjo3r+pPOByUBXOUlxp9 GWEKKIrJ4eogqkVNSixN16VYK7xR+5OUkBYUO+sE6etSxCr7BahMPKxH+XPlZZjKrxciaWQb +dElz3Ab4Opl+ZT/bK2huX+W+NJBEBVzjTkhjSTjcyRdxvS1gwWRuXqAml/sh+KQjPV1PPHF YK5LcqLkle+OKTCa82OvUb7cr+ALxATIZXQkgmn+zFT8UzSS3aiBBohg3BtbTIWy51jNlYdy ezUZ4UxKSsFuUTPt+JjHQBvF7WKbmNGS3fCid5Iag4tWOfZoqiCNzxApkVugltxoc6rG2TyX CmI2rP0mQ0GOsGXA3+3c1MCdQFzdIn/5tLBZyKy4F54UFo35eOX8/g7OaE+xrgY/4bZjpxC1 1pd66AAtKb3aNXpHvIfkVV6NYloo52H+FUE5ZDPNCGD0/btFGPWmWRmkPybzColTy7fmPaGz cBcEEqHK4T0aY4UJmE7Ylvg255Kz7s6wGZe6IR3N0cKNv++O7QARAQABtCVGZXJydWggWWln aXQgPGZlcnJ1aC55aWdpdEBpbnRlbC5jb20+iQJsBBMBCgBWAhsDAh4BAheABQsJCAcDBRUK CQgLBRYCAwEABQkKqZZ8FiEE0jZTh0IuwoTjmYHH+TPrQ98TYR8FAl6ha3sXGHZrczovL2tl eXMub3BlbnBncC5vcmcACgkQ+TPrQ98TYR8uLA//QwltuFliUWe60xwmu9sY38c1DXvX67wk UryQ1WijVdIoj4H8cf/s2KtyIBjc89R254KMEfJDao/LrXqJ69KyGKXFhFPlF3VmFLsN4XiT PSfxkx8s6kHVaB3O183p4xAqnnl/ql8nJ5ph9HuwdL8CyO5/7dC/MjZ/mc4NGq5O9zk3YRGO lvdZAp5HW9VKW4iynvy7rl3tKyEqaAE62MbGyfJDH3C/nV/4+mPc8Av5rRH2hV+DBQourwuC ci6noiDP6GCNQqTh1FHYvXaN4GPMHD9DX6LtT8Fc5mL/V9i9kEVikPohlI0WJqhE+vQHFzR2 1q5nznE+pweYsBi3LXIMYpmha9oJh03dJOdKAEhkfBr6n8BWkWQMMiwfdzg20JX0o7a/iF8H 4dshBs+dXdIKzPfJhMjHxLDFNPNH8zRQkB02JceY9ESEah3wAbzTwz+e/9qQ5OyDTQjKkVOo cxC2U7CqeNt0JZi0tmuzIWrfxjAUulVhBmnceqyMOzGpSCQIkvalb6+eXsC9V1DZ4zsHZ2Mx Hi+7pCksdraXUhKdg5bOVCt8XFmx1MX4AoV3GWy6mZ4eMMvJN2hjXcrreQgG25BdCdcxKgqp e9cMbCtF+RZax8U6LkAWueJJ1QXrav1Jk5SnG8/5xANQoBQKGz+yFiWcgEs9Tpxth15o2v59 gXK5Ag0EV9ZMvgEQAKc0Db17xNqtSwEvmfp4tkddwW9XA0tWWKtY4KUdd/jijYqc3fDD54ES YpV8QWj0xK4YM0dLxnDU2IYxjEshSB1TqAatVWz9WtBYvzalsyTqMKP3w34FciuL7orXP4Ai bPtrHuIXWQOBECcVZTTOdZYGAzaYzxiAONzF9eTiwIqe9/oaOjTwTLnOarHt16QApTYQSnxD UQljeNvKYt1lZE/gAUUxNLWsYyTT+22/vU0GDUahsJxs1+f1yEr+OGrFiEAmqrzpF0lCS3f/ 3HVTU6rS9cK3glVUeaTF4+1SK5ZNO35piVQCwphmxa+dwTG/DvvHYCtgOZorTJ+OHfvCnSVj sM4kcXGjJPy3JZmUtyL9UxEbYlrffGPQI3gLXIGD5AN5XdAXFCjjaID/KR1c9RHd7Oaw0Pdc q9UtMLgM1vdX8RlDuMGPrj5sQrRVbgYHfVU/TQCk1C9KhzOwg4Ap2T3tE1umY/DqrXQgsgH7 1PXFucVjOyHMYXXugLT8YQ0gcBPHy9mZqw5mgOI5lCl6d4uCcUT0l/OEtPG/rA1lxz8ctdFB VOQOxCvwRG2QCgcJ/UTn5vlivul+cThi6ERPvjqjblLncQtRg8izj2qgmwQkvfj+h7Ex88bI 8iWtu5+I3K3LmNz/UxHBSWEmUnkg4fJlRr7oItHsZ0ia6wWQ8lQnABEBAAGJAjwEGAEKACYC GwwWIQTSNlOHQi7ChOOZgcf5M+tD3xNhHwUCXqFrngUJCKxSYAAKCRD5M+tD3xNhH3YWD/9b cUiWaHJasX+OpiuZ1Li5GG3m9aw4lR/k2lET0UPRer2Jy1JsL+uqzdkxGvPqzFTBXgx/6Byz EMa2mt6R9BCyR286s3lxVS5Bgr5JGB3EkpPcoJT3A7QOYMV95jBiiJTy78Qdzi5LrIu4tW6H o0MWUjpjdbR01cnj6EagKrDx9kAsqQTfvz4ff5JIFyKSKEHQMaz1YGHyCWhsTwqONhs0G7V2 0taQS1bGiaWND0dIBJ/u0pU998XZhmMzn765H+/MqXsyDXwoHv1rcaX/kcZIcN3sLUVcbdxA WHXOktGTQemQfEpCNuf2jeeJlp8sHmAQmV3dLS1R49h0q7hH4qOPEIvXjQebJGs5W7s2vxbA 5u5nLujmMkkfg1XHsds0u7Zdp2n200VC4GQf8vsUp6CSMgjedHeF9zKv1W4lYXpHp576ZV7T GgsEsvveAE1xvHnpV9d7ZehPuZfYlP4qgo2iutA1c0AXZLn5LPcDBgZ+KQZTzm05RU1gkx7n gL9CdTzVrYFy7Y5R+TrE9HFUnsaXaGsJwOB/emByGPQEKrupz8CZFi9pkqPuAPwjN6Wonokv ChAewHXPUadcJmCTj78Oeg9uXR6yjpxyFjx3vdijQIYgi5TEGpeTQBymLANOYxYWYOjXk+ae dYuOYKR9nbPv+2zK9pwwQ2NXbUBystaGyQ== Message-ID: Date: Mon, 6 Jul 2020 18:19:17 +0100 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Subject: Re: [dpdk-dev] [PATCH v2 1/5] app/testpmd: clock gettime call in throughput calculation X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" On 7/6/2020 5:53 PM, Honnappa Nagarahalli wrote: > Hi Ferruh, > Thanks for your comments. > > > >> Subject: Re: [PATCH v2 1/5] app/testpmd: clock gettime call in throughput >> calculation >> >> On 6/26/2020 11:09 PM, Honnappa Nagarahalli wrote: >>> The throughput calculation requires a counter that measures passing of >>> time. However, the kernel saves and restores the PMU state when a >>> thread is unscheduled and scheduled. This ensures that the PMU cycles >>> are not counted towards a thread that is not scheduled. Hence, when >>> RTE_ARM_EAL_RDTSC_USE_PMU is enabled, the PMU cycles do not >> represent >>> the passing of time. >> >> Does this mean 'rte_rdtsc()' is broken for Arm? > It depends on the kernel I think. IMO, for isolated CPUs it should be fine. It is currently getting fixed through a kernel patch. Once the kernel patch is up streamed, we will make the required changes in DPDK. > >> Wouldn't it cause more serious issue than testpmd throughput stats? > Within DPDK, it does not seem to be used for anything critical (I have fixed one). OK, thanks for clarification. > >> >>> This results in incorrect calculation of throughput numbers. >>> Use clock_gettime system call to calculate the time passed since last >>> call. >>> >>> Bugzilla ID: 450 >>> Fixes: 0e106980301d ("app/testpmd: show throughput in port stats") >>> Cc: zhihong.wang@intel.com >>> Cc: stable@dpdk.org >>> >>> Signed-off-by: Honnappa Nagarahalli >>> Reviewed-by: Phil Yang >>> Reviewed-by: Ruifeng Wang >>> Tested-by: Phil Yang >>> Tested-by: Ali Alnubani >> >> <...> >> >>> @@ -195,10 +204,17 @@ nic_stats_display(portid_t port_id) >>> } >>> } >>> >>> - diff_cycles = prev_cycles[port_id]; >>> - prev_cycles[port_id] = rte_rdtsc(); >>> - if (diff_cycles > 0) >>> - diff_cycles = prev_cycles[port_id] - diff_cycles; >>> + diff_ns = 0; >>> + if (clock_gettime(CLOCK_TYPE_ID, &cur_time) == 0) { >> >> I guess 'rte_rdtsc()' is faster, but since this is not in the data path, I think it is >> OK. >> >> <...> >> >>> @@ -217,10 +233,10 @@ nic_stats_display(portid_t port_id) >>> (stats.obytes - prev_bytes_tx[port_id]) : 0; >>> prev_bytes_rx[port_id] = stats.ibytes; >>> prev_bytes_tx[port_id] = stats.obytes; >>> - mbps_rx = diff_cycles > 0 ? >>> - diff_bytes_rx * rte_get_tsc_hz() / diff_cycles : 0; >>> - mbps_tx = diff_cycles > 0 ? >>> - diff_bytes_tx * rte_get_tsc_hz() / diff_cycles : 0; >>> + mbps_rx = diff_ns > 0 ? >>> + (double)diff_bytes_rx / diff_ns * NS_PER_SEC : 0; >>> + mbps_tx = diff_ns > 0 ? >>> + (double)diff_bytes_tx / diff_ns * NS_PER_SEC : 0; >> >> The calculation also fixes other issue in the stats. >> With previous method, if the sampling between two stats is a little long, >> "diff_pkts_rx * rte_get_tsc_hz()" can overflow and produce wrong 'bps'. >> >> >> Reviewed-by: Ferruh Yigit