From patchwork Tue Mar 26 14:30:42 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mateusz Polchlopek X-Patchwork-Id: 13604293 X-Patchwork-Delegate: kuba@kernel.org Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.12]) (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 0C7E413C3FC for ; Tue, 26 Mar 2024 14:40:37 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=192.198.163.12 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1711464039; cv=none; b=egH2Pz8tI5WqCBmgch6WzlDrps0Az4H8ph4vdNrpwPlHsqwzHUPUrU5n8XsZGyQvwvH29MWpMaOz9Q/WPV/Bf66N7z59lfhTF7m58xoutA7sb3/339IzcM9pF3s1bErf1imVgv6OTWNK/52yClEA/lz5WzLmUn1wzUitwkokZQA= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1711464039; c=relaxed/simple; bh=ayp3w+xzqn0hd9fHMdrwa/nbYUX3VcDmHtiOLt5hPWs=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=b4I+vpulZ2C0jyYxZ9ukm6vrl3MQknbtEcDzE7vU8pnE2lpFBGMYnyFB1tR5gtLf7pHqEj/MnEiWlAjgs7S+oeNFOhj4pMPHf+FaYbrHVdjr/7wTnVMB+YPBDWKrRULibRm0jKSq/xXSCVFZtJ0m+j9cJnsf2zoyx1JRrA7yt78= 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=NYIGPu5b; arc=none smtp.client-ip=192.198.163.12 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="NYIGPu5b" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1711464038; x=1743000038; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=ayp3w+xzqn0hd9fHMdrwa/nbYUX3VcDmHtiOLt5hPWs=; b=NYIGPu5b9eaGcda2XVwTr1Vn8vEwC8/aWkhoSbxBBXUltDIWUiE19qWr +OM0Q8UL2L7BMQgIFr1UCotpQg4uqNHZrcpMWezTLsvRvC930/Mii2QKa Q5+Pm1JrpfEAbaQfSgmao5BCN1ShKDedSyygDar5sJRPNGxMet9S0kbZM XF/IBCaKRK12aX58msCfmd+27tD6Uur+PW/fOmvfYK3DhVoeDoZf5wE/J ZFw2WauoNiHwmbYsevFulNoQWfZULP2TUseY0659X/wGBzM1QshBgMmQJ 3KPt+qlJy7Bu8I5EC4JjlBW/Ffc1Shdor7NzYGgi+A6TziTbmz6wjHltg w==; X-CSE-ConnectionGUID: wgTsipWmQN6KwPkUTK7csg== X-CSE-MsgGUID: 1TyFJTS5Rs2N2M3Sh8e8wQ== X-IronPort-AV: E=McAfee;i="6600,9927,11025"; a="10296889" X-IronPort-AV: E=Sophos;i="6.07,156,1708416000"; d="scan'208";a="10296889" Received: from orviesa006.jf.intel.com ([10.64.159.146]) by fmvoesa106.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 26 Mar 2024 07:40:27 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.07,156,1708416000"; d="scan'208";a="16412479" Received: from irvmail002.ir.intel.com ([10.43.11.120]) by orviesa006.jf.intel.com with ESMTP; 26 Mar 2024 07:40:23 -0700 Received: from fedora.igk.intel.com (Metan_eth.igk.intel.com [10.123.220.124]) by irvmail002.ir.intel.com (Postfix) with ESMTP id C4C322819E; Tue, 26 Mar 2024 14:40:21 +0000 (GMT) From: Mateusz Polchlopek To: intel-wired-lan@lists.osuosl.org Cc: netdev@vger.kernel.org, anthony.l.nguyen@intel.com, 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, Jiri Pirko , Mateusz Polchlopek Subject: [Intel-wired-lan] [PATCH net-next v8 6/6] ice: Document tx_scheduling_layers parameter Date: Tue, 26 Mar 2024 10:30:42 -0400 Message-Id: <20240326143042.9240-7-mateusz.polchlopek@intel.com> X-Mailer: git-send-email 2.38.1 In-Reply-To: <20240326143042.9240-1-mateusz.polchlopek@intel.com> References: <20240326143042.9240-1-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 Acked-by: Jakub Kicinski Reviewed-by: Jiri Pirko Reviewed-by: Przemek Kitszel Co-developed-by: Mateusz Polchlopek Signed-off-by: Mateusz Polchlopek --- 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 7f30ebd5debb..830c04354222 100644 --- a/Documentation/networking/devlink/ice.rst +++ b/Documentation/networking/devlink/ice.rst @@ -21,6 +21,53 @@ Parameters * - ``enable_iwarp`` - runtime - mutually exclusive with ``enable_roce`` + * - ``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 do PCI slot powercycle 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 =============