From patchwork Wed Feb 28 14:20:54 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mateusz Polchlopek X-Patchwork-Id: 13575607 X-Patchwork-Delegate: kuba@kernel.org Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.14]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id CE3CE2AD00 for ; Wed, 28 Feb 2024 14:30:08 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.175.65.14 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1709130610; cv=none; b=dPj+v+7cn/3Aa8EPuY+RGwyugoNcMnvTfkqt1dZJcY88Zk4SxgXrjTnctCGfdC3ju9ubITI3ITSQ9e24iQR7wNixNQiECT+FYQ/gCjn+G0d8Cc+CRSzA67iSxRoM/wee/OEyPGD10vKig3CEa71WAGu2A4l8Pq30+OtPIj/WDAs= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1709130610; c=relaxed/simple; bh=zLfIHt2dGuwOkbpC/bp3U0IB/u6iLNKIZuLuNDYezO0=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=jjbJtjBEc1jYuLQGT/O587cXpuSJbiY9JP2k6bLP0AnojYPdUxP7zwq/660/oPJfpHi5tUGWjhQU0IB/IgyzqAybmcMf8Mbo91tQi37mMa+GV4tt2Yrl+dXt9H3OCF1TudAx7HcWZR1d17SoIGNgu3iY8te2ZjSzbcOURgNsfpY= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com; spf=pass smtp.mailfrom=intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=CmGChUDp; arc=none smtp.client-ip=198.175.65.14 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="CmGChUDp" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1709130608; x=1740666608; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=zLfIHt2dGuwOkbpC/bp3U0IB/u6iLNKIZuLuNDYezO0=; b=CmGChUDp2A17RcV3yRL7awRFaS2tJpwH29XV5PB8sv37JXZcYOoi0Ld9 Z4negFGApH1R2vItTEVhTQUfovFhpTazxdFsZlfQsk3g0enxjXSLydDVh OgxiegQQ770mnXlI6a9AWG1WYDik49O5GZKkvrrQGc8SXQYgkQn37qhNw RfwzS2UE46anGnDDBiwgEsfCanWNiLfIDdZWvj6SGJKE7b5YBZ2JqENkX SofcTULdj9BIw1MtHjKlSaV5HGRJb1xSwDX9G0PuDl2t1XmFo1Vhy5rNx 6AyhQlZ49pazAkkCURXx9H3nbfMCdf6vi+2DM91DvztEqG8Z96mwEhFen A==; X-IronPort-AV: E=McAfee;i="6600,9927,10998"; a="7354557" X-IronPort-AV: E=Sophos;i="6.06,190,1705392000"; d="scan'208";a="7354557" Received: from fmviesa006.fm.intel.com ([10.60.135.146]) by orvoesa106.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 28 Feb 2024 06:30:08 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.06,190,1705392000"; d="scan'208";a="7659023" Received: from irvmail002.ir.intel.com ([10.43.11.120]) by fmviesa006.fm.intel.com with ESMTP; 28 Feb 2024 06:30:04 -0800 Received: from fedora.igk.intel.com (Metan_eth.igk.intel.com [10.123.220.124]) by irvmail002.ir.intel.com (Postfix) with ESMTP id B7EF836342; Wed, 28 Feb 2024 14:30:03 +0000 (GMT) From: Mateusz Polchlopek To: intel-wired-lan@lists.osuosl.org Cc: netdev@vger.kernel.org, kuba@kernel.org, jiri@resnulli.us, horms@kernel.org, przemyslaw.kitszel@intel.com, andrew@lunn.ch, victor.raj@intel.com, michal.wilczynski@intel.com, lukasz.czapnik@intel.com, Mateusz Polchlopek Subject: [Intel-wired-lan] [PATCH iwl-next v5 5/5] ice: Document tx_scheduling_layers parameter Date: Wed, 28 Feb 2024 09:20:54 -0500 Message-Id: <20240228142054.474626-6-mateusz.polchlopek@intel.com> X-Mailer: git-send-email 2.38.1 In-Reply-To: <20240228142054.474626-1-mateusz.polchlopek@intel.com> References: <20240228142054.474626-1-mateusz.polchlopek@intel.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 From: Michal Wilczynski New driver specific parameter 'tx_scheduling_layers' was introduced. Describe parameter in the documentation. Signed-off-by: Michal Wilczynski Co-developed-by: Mateusz Polchlopek Signed-off-by: Mateusz Polchlopek Acked-by: Jakub Kicinski --- Documentation/networking/devlink/ice.rst | 47 ++++++++++++++++++++++++ 1 file changed, 47 insertions(+) diff --git a/Documentation/networking/devlink/ice.rst b/Documentation/networking/devlink/ice.rst index efc6be109dc3..c9253e1f61c9 100644 --- a/Documentation/networking/devlink/ice.rst +++ b/Documentation/networking/devlink/ice.rst @@ -36,6 +36,53 @@ Parameters The latter allows for bandwidth higher than external port speed when looping back traffic between VFs. Works with 8x10G and 4x25G cards. + * - ``tx_scheduling_layers`` + - permanent + - The ice hardware uses hierarchical scheduling for Tx with a fixed + number of layers in the scheduling tree. Each of them are decision + points. Root node represents a port, while all the leaves represent + the queues. This way of configuring the Tx scheduler allows features + like DCB or devlink-rate (documented below) to configure how much + bandwidth is given to any given queue or group of queues, enabling + fine-grained control because scheduling parameters can be configured + at any given layer of the tree. + + The default 9-layer tree topology was deemed best for most workloads, + as it gives an optimal ratio of performance to configurability. However, + for some specific cases, this 9-layer topology might not be desired. + One example would be sending traffic to queues that are not a multiple + of 8. Because the maximum radix is limited to 8 in 9-layer topology, + the 9th queue has a different parent than the rest, and it's given + more bandwidth credits. This causes a problem when the system is + sending traffic to 9 queues: + + | tx_queue_0_packets: 24163396 + | tx_queue_1_packets: 24164623 + | tx_queue_2_packets: 24163188 + | tx_queue_3_packets: 24163701 + | tx_queue_4_packets: 24163683 + | tx_queue_5_packets: 24164668 + | tx_queue_6_packets: 23327200 + | tx_queue_7_packets: 24163853 + | tx_queue_8_packets: 91101417 < Too much traffic is sent from 9th + + To address this need, you can switch to a 5-layer topology, which + changes the maximum topology radix to 512. With this enhancement, + the performance characteristic is equal as all queues can be assigned + to the same parent in the tree. The obvious drawback of this solution + is a lower configuration depth of the tree. + + Use the ``tx_scheduling_layer`` parameter with the devlink command + to change the transmit scheduler topology. To use 5-layer topology, + use a value of 5. For example: + $ devlink dev param set pci/0000:16:00.0 name tx_scheduling_layers + value 5 cmode permanent + Use a value of 9 to set it back to the default value. + + You must reboot the system for the selected topology to take effect. + + To verify that value has been set: + $ devlink dev param show pci/0000:16:00.0 name tx_scheduling_layers Info versions =============