From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mails.dpdk.org (mails.dpdk.org [217.70.189.124]) by inbox.dpdk.org (Postfix) with ESMTP id A2FB6A034F; Tue, 30 Mar 2021 21:39:54 +0200 (CEST) Received: from [217.70.189.124] (localhost [127.0.0.1]) by mails.dpdk.org (Postfix) with ESMTP id 9FCA5140F9C; Tue, 30 Mar 2021 21:37:23 +0200 (CEST) Received: from mga14.intel.com (mga14.intel.com [192.55.52.115]) by mails.dpdk.org (Postfix) with ESMTP id 9628D140F0F for ; Tue, 30 Mar 2021 21:36:55 +0200 (CEST) IronPort-SDR: tjM5+/4c1pM/VktwFEvpxKLRNWYZcBeAg+D1YDyIjUbj2SoFy0nOzoTbBpjPAvy8rN3samUEsw WxHCi+PG8aeQ== X-IronPort-AV: E=McAfee;i="6000,8403,9939"; a="191315891" X-IronPort-AV: E=Sophos;i="5.81,291,1610438400"; d="scan'208";a="191315891" Received: from orsmga008.jf.intel.com ([10.7.209.65]) by fmsmga103.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 30 Mar 2021 12:36:52 -0700 IronPort-SDR: uc/ULXxzpu6SNGRulBbeIaJypQCtBw+EuGYIp6e/SAZnYHoipFAJU4hD8xV1psdYOHSperWZEx /RuhOmsVzfjA== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.81,291,1610438400"; d="scan'208";a="418309802" Received: from txasoft-yocto.an.intel.com ([10.123.72.192]) by orsmga008.jf.intel.com with ESMTP; 30 Mar 2021 12:36:51 -0700 From: Timothy McDaniel To: Cc: dev@dpdk.org, erik.g.carrillo@intel.com, gage.eads@intel.com, harry.van.haaren@intel.com, jerinj@marvell.com, thomas@monjalon.net Date: Tue, 30 Mar 2021 14:35:39 -0500 Message-Id: <1617132940-24800-27-git-send-email-timothy.mcdaniel@intel.com> X-Mailer: git-send-email 1.7.10 In-Reply-To: <1617132940-24800-1-git-send-email-timothy.mcdaniel@intel.com> References: <20210316221857.2254-2-timothy.mcdaniel@intel.com> <1617132940-24800-1-git-send-email-timothy.mcdaniel@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Subject: [dpdk-dev] =?utf-8?q?=5BPATCH_v2_26/27=5D_doc/dlb2=3A_update_doc?= =?utf-8?q?umentation_for_v2=2E5?= X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.29 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" Update the dlb documentation for v2.5. Notable differences include the new cobined credit scheme. Also cleaned up a couple of sections, and removed a duplicate section. Signed-off-by: Timothy McDaniel --- doc/guides/eventdevs/dlb2.rst | 75 +++++++++++++---------------------- 1 file changed, 27 insertions(+), 48 deletions(-) diff --git a/doc/guides/eventdevs/dlb2.rst b/doc/guides/eventdevs/dlb2.rst index 94d2c77ff..94e46ea7d 100644 --- a/doc/guides/eventdevs/dlb2.rst +++ b/doc/guides/eventdevs/dlb2.rst @@ -4,7 +4,8 @@ Driver for the Intel® Dynamic Load Balancer (DLB2) ================================================== -The DPDK dlb poll mode driver supports the Intel® Dynamic Load Balancer. +The DPDK dlb poll mode driver supports the Intel® Dynamic Load Balancer, +hardware versions 2.0 and 2.5. Prerequisites ------------- @@ -35,7 +36,7 @@ eventdev API and DLB2 misalign. Scheduling Domain Configuration ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -There are 32 scheduling domainis the DLB2. +DLB2 supports 32 scheduling domains. When one is configured, it allocates load-balanced and directed queues, ports, credits, and other hardware resources. Some resource allocations are user-controlled -- the number of queues, for example @@ -67,42 +68,7 @@ If the ``RTE_EVENT_QUEUE_CFG_ALL_TYPES`` flag is not set, schedule_type dictates the queue's scheduling type. The ``nb_atomic_order_sequences`` queue configuration field sets the ordered -queue's reorder buffer size. DLB2 has 4 groups of ordered queues, where each -group is configured to contain either 1 queue with 1024 reorder entries, 2 -queues with 512 reorder entries, and so on down to 32 queues with 32 entries. - -When a load-balanced queue is created, the PMD will configure a new sequence -number group on-demand if num_sequence_numbers does not match a pre-existing -group with available reorder buffer entries. If all sequence number groups are -in use, no new group will be created and queue configuration will fail. (Note -that when the PMD is used with a virtual DLB2 device, it cannot change the -sequence number configuration.) - -The queue's ``nb_atomic_flows`` parameter is ignored by the DLB2 PMD, because -the DLB2 does not limit the number of flows a queue can track. In the DLB2, all -load-balanced queues can use the full 16-bit flow ID range. - -Load-Balanced Queues -~~~~~~~~~~~~~~~~~~~~ - -A load-balanced queue can support atomic and ordered scheduling, or atomic and -unordered scheduling, but not atomic and unordered and ordered scheduling. A -queue's scheduling types are controlled by the event queue configuration. - -If the user sets the ``RTE_EVENT_QUEUE_CFG_ALL_TYPES`` flag, the -``nb_atomic_order_sequences`` determines the supported scheduling types. -With non-zero ``nb_atomic_order_sequences``, the queue is configured for atomic -and ordered scheduling. In this case, ``RTE_SCHED_TYPE_PARALLEL`` scheduling is -supported by scheduling those events as ordered events. Note that when the -event is dequeued, its sched_type will be ``RTE_SCHED_TYPE_ORDERED``. Else if -``nb_atomic_order_sequences`` is zero, the queue is configured for atomic and -unordered scheduling. In this case, ``RTE_SCHED_TYPE_ORDERED`` is unsupported. - -If the ``RTE_EVENT_QUEUE_CFG_ALL_TYPES`` flag is not set, schedule_type -dictates the queue's scheduling type. - -The ``nb_atomic_order_sequences`` queue configuration field sets the ordered -queue's reorder buffer size. DLB2 has 4 groups of ordered queues, where each +queue's reorder buffer size. DLB2 has 2 groups of ordered queues, where each group is configured to contain either 1 queue with 1024 reorder entries, 2 queues with 512 reorder entries, and so on down to 32 queues with 32 entries. @@ -157,6 +123,11 @@ type (atomic, ordered, or parallel) is not preserved, and an event's sched_type will be set to ``RTE_SCHED_TYPE_ATOMIC`` when it is dequeued from a directed port. +Finally, even though all 3 event types are supported on the same QID by +converting unordered events to ordered, such use should be discouraged as much +as possible, since mixing types on the same queue uses valuable reorder +resources, and orders events which do not require ordering. + Flow ID ~~~~~~~ @@ -169,13 +140,15 @@ Hardware Credits DLB2 uses a hardware credit scheme to prevent software from overflowing hardware event storage, with each unit of storage represented by a credit. A port spends a credit to enqueue an event, and hardware refills the ports with credits as the -events are scheduled to ports. Refills come from credit pools, and each port is -a member of a load-balanced credit pool and a directed credit pool. The -load-balanced credits are used to enqueue to load-balanced queues, and directed -credits are used for directed queues. +events are scheduled to ports. Refills come from credit pools. -A DLB2 eventdev contains one load-balanced and one directed credit pool. These -pools' sizes are controlled by the nb_events_limit field in struct +For DLB v2.5, there is a single credit pool used for both load balanced and +directed traffic. + +For DLB v2.0, each port is a member of both a load-balanced credit pool and a +directed credit pool. The load-balanced credits are used to enqueue to +load-balanced queues, and directed credits are used for directed queues. +These pools' sizes are controlled by the nb_events_limit field in struct rte_event_dev_config. The load-balanced pool is sized to contain nb_events_limit credits, and the directed pool is sized to contain nb_events_limit/4 credits. The directed pool size can be overridden with the @@ -276,10 +249,16 @@ The DLB2 supports event priority and per-port queue service priority, as described in the eventdev header file. The DLB2 does not support 'global' event queue priority established at queue creation time. -DLB2 supports 8 event and queue service priority levels. For both priority -types, the PMD uses the upper three bits of the priority field to determine the -DLB2 priority, discarding the 5 least significant bits. The 5 least significant -event priority bits are not preserved when an event is enqueued. +DLB2 supports 4 event and queue service priority levels. For both priority types, +the PMD uses the upper three bits of the priority field to determine the DLB2 +priority, discarding the 5 least significant bits. But least significant bit out +of 3 priority bits is effectively ignored for binning into 4 priorities. The +discarded 5 least significant event priority bits are not preserved when an event +is enqueued. + +Note that event priority only works within the same event type. +When atomic and ordered or unordered events are enqueued to same QID, priority +across the types is always equal, and both types are served in a round robin manner. Reconfiguration ~~~~~~~~~~~~~~~ -- 2.23.0