From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.15]) (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 090485647F for ; Fri, 8 Mar 2024 11:47:45 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=192.198.163.15 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1709898468; cv=none; b=So0qu1UaYh7iP//kaCRNNcLrqaT9wxiKwhJrgjoRovkIgvVoNOUXVWY9Gho5Kwhy3owC5kHWSlpioslQ8//0Sa167swcInQWIfYdtA1sfcr6HyqPEARul3jbSRG4DgEQug8B1QvkiIm03c1Jrlkjh/TU6VOPNsqxKNY1YmOnSSQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1709898468; c=relaxed/simple; bh=wkr6lOyqSC8jTNXgtiotMJJJznG/KbVhia8zrYkWnLY=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=RxNUQlMG/VR1105eV1zbsDFwD25Xc+w/T8VaePqyr+wSS1CAtwP972roQ93g1I8asEXELFElviSUrsrSYE4jlVtHlDN9y+7wJaK8aguxFBf7P7slmCk3ZNnoPlGtawoS9PRaO0FQlOCddFAi6qVJRxunfOB+Z0aik+N7HbEtyFI= 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=SpbIMVsy; arc=none smtp.client-ip=192.198.163.15 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="SpbIMVsy" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1709898466; x=1741434466; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=wkr6lOyqSC8jTNXgtiotMJJJznG/KbVhia8zrYkWnLY=; b=SpbIMVsyrBmaqGMcwkIUntGNWgxWvsqL8O26ShNYvXKR1KAeU7a3CCQH Urg9sYnjJmw0F0iRcZ+A6MC73tHQn6xm/siLwCqWELmC8llRleZYsrN4D Ufub0YQGighYXdQw1h6BNbayBRweb3rhngjtAnZEsCMHVt0RzifycYTfM kh1iUuW9oipgnMBmtij//a92zBve9rjN4ZUUBlziz5smf6Vz6Mj3O4G0t sGwDjJXxUzWVx54qzOFuv9tqlmmSK2XxfN4LoHsaxdVs61n/907+NvFFq mHavuEgpTGg5xg93kf9wZz4osAKC8JfikIpnc8A+mCl3C8e22lyMUddJZ g==; X-IronPort-AV: E=McAfee;i="6600,9927,11006"; a="4782428" X-IronPort-AV: E=Sophos;i="6.07,109,1708416000"; d="scan'208";a="4782428" Received: from orviesa006.jf.intel.com ([10.64.159.146]) by fmvoesa109.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 08 Mar 2024 03:47:45 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.07,109,1708416000"; d="scan'208";a="10849547" Received: from irvmail002.ir.intel.com ([10.43.11.120]) by orviesa006.jf.intel.com with ESMTP; 08 Mar 2024 03:47:42 -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 6D666312EB; Fri, 8 Mar 2024 11:47:40 +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 iwl-next v7 6/6] ice: Document tx_scheduling_layers parameter Date: Fri, 8 Mar 2024 06:39:19 -0500 Message-Id: <20240308113919.11787-7-mateusz.polchlopek@intel.com> X-Mailer: git-send-email 2.38.1 In-Reply-To: <20240308113919.11787-1-mateusz.polchlopek@intel.com> References: <20240308113919.11787-1-mateusz.polchlopek@intel.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 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 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 ============= -- 2.38.1