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Latest InfiniBand and RoCE Developments a Major Focus at the OpenFabrics Alliance Workshop 2018

May 31st, 2018

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The annual OpenFabrics Alliance (OFA) Workshop is a premier means of fostering collaboration among those in the OpenFabrics community and advanced networking industry as a whole. Known for being the only event of its kind, the OFA Workshop allows attendees to discuss emerging fabric technologies, collaborate on future industry requirements, and address remaining challenges. The week-long event is made up of sessions covering a wide range of pressing topics, including talks related to InfiniBand and RDMA over Converged Ethernet (RoCE).

This year’s agenda featured sessions highlighting a variety of InfiniBand and RoCE updates and emerging applications. Below is a list of all OFA Workshop 2018 sessions covering RDMA technologies and the associated presentations.


RoCE Containers - Status update

Parav Pandit, Mellanox Technologies

Using RDMA in containerized environment in a secure manner is desired. RDMA over Converged Ethernet (RoCE) needs to operate and honor net namespace other than default init_net. This session focused on recent and upcoming enhancements for functionality and security for RoCE. Various modules of the InfiniBand stack including connection manager, user verbs, core, statistics, resource tracking, device discovery and visibility to applications, net device migration across namespaces at minimum are the key areas to address for supporting RoCE devices in container environment.

Building Efficient Clouds for HPC, Big Data, and Neuroscience Applications over SR-IOV-enabled InfiniBand Clusters

Xiaoyi Lu, The Ohio State University

Single Root I/O Virtualization (SR-IOV) technology has been steadily gaining momentum for high performance interconnects such as InfiniBand. SR-IOV can deliver near-native performance but lacks locality-aware communication support. This talk presented an efficient approach to building HPC clouds based on MVAPICH2 and RDMA-Hadoop with SR-IOV. The talk highlighted high-performance designs of the virtual machine and container aware MVAPICH2 library over SR-IOV enabled HPC Clouds. This talk also presented a high-performance virtual machine migration framework for MPI applications on SR-IOV enabled InfiniBand clouds. The presenter discussed how to leverage the high-performance networking features (e.g., RDMA, SR-IOV) on cloud environments to accelerate data processing through RDMA-Hadoop package. To show the performance benefits of the proposed designs, they co-designed a scalable and distributed tool with MVAPICH2 for statistical evaluation of brain connectomes in the Neuroscience domain, which can run on top of container-based cloud environments with natively utilizing RDMA interconnects and delivering near-native performance.

Non-Contiguous Memory Registration

Tzahi Oved, Mellanox Technologies

Memory registration enables contiguous memory regions to be accessed with RDMA. In this talk, they showed how this could be extended beyond access rights, for describing complex memory layouts. Many HPC applications receive regular structured data, such as a column of a matrix. In this case, the application would typically receive a chunk of data and scatter it by the CPU, or use multiple RDMA writes to transfer each element in-place. Both options introduce significant overhead. By using a memory region that specifies strided access, this overhead could be completely eliminated: the initiator posts a single RDMA write and the target HCA scatters each element into place. Similarly, standard memory regions cannot describe non-contiguous memory allocations, forcing applications to generate remote keys for each buffer. However, by allowing a non-contiguous memory region to span multiple address ranges, an application may scatter remote data with a single remote key. Using non-contiguous memory registration, such memory layouts may be created, accessed, and invalidated using efficient, non-privileged, user-level interfaces.

Dynamically-Connected Transport

Alex Rosenbaum, Mellanox Technologies

Dynamically-Connected (DC) transport is a combination of features from the existing UD and RC transports: DC can send every message to a different destination, like UD does, and is also a reliable transport - supporting RDMA and Atomic operations as RC does. The crux of the transport is dynamically connecting and disconnecting on-the-fly in hardware when changing destinations. As a result, a DC endpoint may communicate with any peer, providing the full RC feature set, and maintain a fixed memory footprint regardless of the size of the network. In this talk, we present the unique characteristics of this new transport, and show how it could be leveraged to reach peek all-to all communication performance. We will review the DC transport objects and their semantics, the Linux upstream DC API and its usage.

T10-DIF offload

Tzahi Oved, Mellanox Technologies

T10-DIF is a standard that defines how to protect the integrity of storage data blocks. Every storage block is proceeded by a Data Integrity Field (DIF). This field contains CRC of the preceding block, the LBA (block number within the storage device) and an application tag. Normally the DIF will be saved in the storage device along with the data block itself, so that in the future it will be used to verify the data integrity.

Modern storage systems and adapters allow creating, verifying and stripping those DIFs while reading and writing data to the storage device, as requested by the user and supported by the OS. The T10-DIF offload RDMA feature brings this capability to the RDMA based storage protocols. Using this feature, RDMA based protocols can request the RDMA device to generate, strip and/or verify DIF while sending or receiving a message. DIF operation is configured in a new Signature Memory-Region. Every memory access using this MR (local or remote) results in DIF operation done on the data as it moves between wire and memory. This session will describe how the configuration and operation of this feature should be done using verbs API.

NVMf Target Offload

Liran Liss, Mellanox Technologies

NVMe is a standard that defines how to access a solid-state storage device over PCI in a very efficient way. It defines how to create and use multiple submission and completion queues between software and the device over which storage operations are carried and completed.

NVMe-over-Fabric is a newer standard that maps NVMe to RDMA to allow remote access to storage devices over an RDMA fabric using the same NVMe language. Since NVMe queues look and act very much like RDMA queues, it is a natural application to bridge between the two. In fact, a couple of software packages today implement an NVMe-over-Fabric to local NVMe target.

The NVMe-oF Target Offload feature is such an implementation that is done in hardware. A supporting RDMA device is configured with the details of the queues of an NVMe device. An incoming client RDMA connection (QP) is then bound to those NVMe queues. From that point on, every IO request arriving over the network from the client is submitted to the respective NVMe queue without any software intervention using PCI peer-to-peer access. This session will describe how the configuration and operation of such feature should be done using verbs.

High-Performance Big Data Analytics with RDMA over NVM and NVMe-SSD

Xiaoyi Lu, The Ohio State University

The convergence of Big Data and HPC has been pushing the innovation of accelerating Big Data analytics and management on modern HPC clusters. Recent studies have shown that the performance of Apache Hadoop, Spark, and Memcached can be significantly improved by leveraging the high performance networking technologies, such as Remote Direct Memory Access (RDMA). Most of these studies are based on `DRAM+RDMA’ schemes. On the other hand, Non-Volatile Memory (NVM)and NVMe-SSD technologies can support RDMA access with low-latency, high-throughput, and persistence on HPC clusters. NVMs and NVMe-SSDs provide the opportunity to build novel high-performance and QoS-aware communication and I/O subsystems for data-intensive applications. In this talk, we proposed new communication and I/O schemes for these data analytics stacks, which are designed with RDMA over NVM and NVMe-SSD. Our studies show that the proposed designs can significantly improve the communication, I/O, and application performance for Big Data analytics and management middleware, such as Hadoop, Spark, Memcached, etc. In addition, we will also discuss how to design QoS-aware schemes in these frameworks with NVMe-SSD.

Comprehensive, Synchronous, High Frequency Measurement of InfiniBand Networks in Production HPC Systems

Michael Aguilar, Sandia National Laboratories

In this presentation, we showed InfiniBand performance information gathered from a large Sandia HPC system, Skybridge. We showed detection of network hot spots that may affect data exchanges for tightly coupled parallel threads. We quantified the overhead cost (application impact) when data is being collected.

At Sandia Labs, we are continuing to develop an InfiniBand fabric switch port sampler that can used to gather remote data from InfiniBand switches. Using coordinated InfiniBand switch and HCA port samplers, a real-time snapshot of InfiniBand traffic can be retrieved from the fabric on a large-scale HPC computing platform. Due to the time-stamped and light-weight data retrieval with LDMS, production job runs can be instrumented to provide research data that can be used to specify computing platforms with improved data performance.

Our implementation of synchronous monitoring of large-scale HPC systems provides insights into how to improve computing performance. Our sampler takes advantage of the OpenFabrics software stack for metric gathering. The OFED stack supports a common inter-operable software stack that provides the inherent ability to gather traffic metrics from selected connection points within a network fabric. We use OFED MAD and UMAD to collect the remote switch port traffic metrics.

The OFA Workshop is extremely valuable to InfiniBand Trade Association members and the fabrics community as a whole with an aim to identify, discuss and overcome the industry’s most significant challenges. We look forward to participating again next year. Videos of each presentation from the OFA Workshop 2018 are now available online on insideHPC.com.

Bill Lee

Author: admin Categories: InfiniBand, OpenFabrics Alliance, RDMA, RoCE Tags:

InfiniBand and RoCE to Make Their Mark at OFA Workshop 2017

March 16th, 2017

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The OpenFabrics Alliance (OFA) workshop is an annual event devoted to advancing the state of the art in networking. The workshop is known for showcasing a broad range of topics all related to network technology and deployment through an interactive, community-driven event. The comprehensive event includes a rich program made up of more than 50 sessions covering a variety of critical networking topics, which range from current deployments of RDMA to new and advanced network technologies.

To view the full list of abstracts, visit the OFA Workshop 2017 Abstracts and Agenda page.

This year’s workshop program will also feature some notable sessions that showcase the latest developments happening for InfiniBand and RoCE technology. Below are is the collection of OFA Workshop 2017 sessions that we recommend you check out:

Developer Experiences of the First Paravirtual RDMA Provider and Other RDMA Updates
Presented by Adit Ranadive, VMware

VMware’s Paravirtual RDMA (PVRDMA) device is a new NIC in vSphere 6.5 that allows VMs in a cluster to communicate using Remote Direct Memory Access (RDMA), while maintaining latencies and bandwidth close to that of physical hardware. Recently, the PVRDMA driver was accepted as part of the Linux 4.10 kernel and our user-library was added as part of the new rdma-core package.

In this session, we will provide a brief overview of our PVRDMA design and capabilities. Next, we will discuss our development approach and challenges for joint device and driver development. Further, we will highlight our experience for upstreaming the driver and library with the new changes to the core RDMA stack.

We will provide an update on the performance of the PVRDMA device along with upcoming updates to the device capabilities. Finally, we will provide new results on the performance achieved by several HPC applications using VM DirectPath I/O.

This session seeks to engage the audience in discussions on: 1) new RDMA provider development and acceptance, and 2) hardware support for RDMA virtualization.

Experiences with NVMe over Fabrics
Presented by Parav Pandit, Mellanox

NVMe is an interface specification to access non-volatile storage media over PCIe buses. The interface enables software to interact with devices using multiple, asynchronous submission and completion queues, which reside in memory. Consequently, software may leverage the inherent parallelism and low latency of modern NMV devices with minimal overhead. Recently, the NMVe specification has been extended to support remote access over fabrics, such as RDMA and Fibre Channel. Using RDMA, NVMe over Fabrics (NVMe-oF) provides the high BW and low-latency characteristics of NVMe to remote devices. Moreover, these performance traits are delivered with negligible CPU overhead as the bulk of the data transfer is conducted by RDMA.

In this session, we present an overview of NVMe-oF and its implementation in Linux. We point out the main design choices and evaluate NVMe-oF performance for both InfiniBand and RoCE fabrics.

Validating RoCEv2 for Production Deployment in the Cloud Datacenter
Presented by Sowmini Varadhan, Oracle

With the increasing prevalence of ethernet switches and NICs in Data Center Networks, we have been experimenting with the deployment of RDMA over Commodity Ethernet (RoCE) in our DCN. RDMA needs a lossless transport, and, in theory, this can be achieved on ethernet by using priority based PFC (IEEE 802.1qbb) and ECN (IETF RFC 3168).

We describe our experiences in trying to deploy these protocols in a RoCEv2 testbed running @ 100 Gbit/sec consisting of a multi-level CLOS network.

In addition to addressing the documented limitations around PFC/ECN (livelock, pause-frame-storm, memory requirements for supporting multiple priority flows), we also hope to share some of the performance metrics gathered, as well as some feedback on ways to improve the tooling for observability and diagnosability of the system in a vendor-agnostic, interoperable way.

Host Based InfiniBand Network Fabric Monitoring
Presented by Michael Aguilar, Sandia National Laboratories

Synchronized host based InfiniBand network counter monitoring of local connections at 1Hz can provide a reasonable system snapshot understanding of traffic injection/ejection into/from the fabric. This type of monitoring is currently used to enable understanding about the data flow characteristics of applications and inference about congestion based on application performance degradation. It cannot, however, enable identification of where congestion occurs or how well adaptive routing algorithms and policies react to and alleviate it. Without this critical information the fabric remains opaque and congestion management will continue to be largely handled through increases in bandwidth. To reduce fabric opacity, we have extended our host based monitoring to include internal InfiniBand fabric network ports. In this presentation we describe our methodology along with preliminary timing and overhead information. Limitations and their sources are discussed along with proposed solutions, optimizations, and planned future work.

IBTA TWG - Recent Topics in the IBTA, and a Look Ahead
Presented by Bill Magro, Intel on behalf of InfiniBand Trade Association

This talk discusses some recent activities in the IBTA including recent specification updates. It also provides a glimpse into the future for the IBTA.

InfiniBand Virtualization
Presented by Liran Liss, Mellanox on behalf of InfiniBand Trade Association

InfiniBand Virtualization allows a single Channel Adapter to present multiple transport endpoints that share the same physical port. To software, these endpoints are exposed as independent Virtual HCAs (VHCAs), and thus may be assigned to different software entities, such as VMs. VHCAs are visible to Subnet Management, and are managed just like physical HCAs. This session provides an overview of the InfiniBand Virtualization Annex, which was released on November 2016. We will cover the Virtualization model, management, addressing modes, and discuss deployment considerations.

IPoIB Acceleration
Presented by Tzahi Oved, Mellanox

The IPoIB protocol encapsulates IP packets over InfiniBand datagrams. As a direct RDMA Upper Layer Protocol (ULP), IPoIB cannot support HW features that are specific to the IP protocol stack. Nevertheless, RDMA interfaces have been extended to support some of the prominent IP offload features, such as TCP/UDP checksum and TSO. This provided reasonable performance for IPoIB.

However, new network interface features are one of the most active areas of the Linux kernel. Examples include TSS and RSS, tunneling offloads, and XDP. In addition, the basic IP offload features are insufficient to cope with the increasing network bandwidth. Rather than continuously porting IP network interface developments into the RDMA stack, we propose adding abstract network data-path interfaces to RDMA devices.

In order to present a consistent interface to users, the IPoIB ULP continues to represent the network device to the IP stack. The common code also manages the IPoIB control plane, such as resolving path queries and registering to multicast groups. Data path operations are forwarded to devices that implement the new API, or fallback to the standard implementation otherwise. Using the forgoing approach, we show how IPoIB closes the performance gap compared to state-of-the-art Ethernet network interfaces.

Packet Processing Verbs for Ethernet and IPoIB
Presented by Tzahi Oved, Mellanox

As a prominent user-level networking API, the RDMA stack has been extended to support packet processing applications and user-level TCP/IP stacks, initially focusing on Ethernet. This allowed delivering low latency and high message-rate to these applications.

In this talk, we provide an extensive introduction to both current and upcoming packet processing Verbs, such as checksum offloads, TSO, flow steering, and RSS. Next, we describe how these capabilities may also be applied to IPoIB traffic.

In contrast to Ethernet support, which was based on Raw Ethernet QPs that receive unmodified packets from the wire, IPoIB packets are sent over a “virtual wire”, managed by the kernel. Thus, processing selective IP flows from user-space requires coordination with the IPoIB interface.

The Linux SoftRoCE Driver
Presented by Liran Liss, Mellanox

SoftRoCE is a software implementation of the RDMA transport protocol over Ethernet. Thus, any host to conduct RDMA traffic without necessitating a RoCE-capable NIC, allowing RDMA development anywhere.

This session presents the Linux SoftRoCE driver, RXE, which was recently accepted to the 4.9 kernel. In addition, the RXE user-level driver is now part of rdma-core, the consolidated RDMA user-space codebase. RXE is fully interoperable with HW RoCE devices, and may be used for both testing and production. We provide an overview of the RXE driver, detail its configuration, and discuss the current status and remaining challenges in RXE development.

Ubiquitous RoCE
Presented by Alex Shpiner, Mellanox

In recent years, the usage of RDMA in datacenter networks has increased significantly, with RoCE (RDMA over Converged Ethernet) emerging as the canonical approach to deploying RDMA in Ethernet-based datacenters.

Initially, RoCE required a lossless fabric for optimal performance. This is typically achieved by enabling Priority Flow Control (PFC) on Ethernet NICs and switches. The RoCEv2 specification introduced RoCE congestion control, which allows throttling transmission rate in response to congestion. Consequently, packet loss may be minimized and performance is maintained even if the underlying Ethernet network is lossy.

In this talk, we discuss the details of latest developments in the RoCE congestion control. Hardware congestion control reduces the latency of the congestion control loop; it reacts promptly in the face of congestion by throttling the transmission rate quickly and accurately; when congestion is relieved, bandwidth is immediately recovered. The short control loop also prevents network buffers from overfilling in many congestion scenarios.

In addition, fast hardware retransmission complements congestion control in heavy congestion scenarios, by significantly reducing the penalty of packet drops.

Keep an eye out as videos of the OFA Workshop 2017 sessions will be published on both the OFA website and insideHPC. Interested in attending? Registration for the 13th Annual OFA Workshop will be available online and onsite up until the opening day of the event, March 27. Visit the OFA Workshop 2017 Registration page for more information.

Bill Lee

Author: admin Categories: InfiniBand, OpenFabrics Alliance, RoCE Tags:

Share Your RDMA Expertise at the 2017 OpenFabrics Alliance Workshop

January 27th, 2017

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Experts from around the world will gather at the 13th Annual OpenFabrics Alliance (OFA) Workshop March 27-31 in Austin, TX to discuss recent innovations in network technology and to tackle the industry’s toughest challenges. Through engaging keynotes, lively sessions, and open discussions, the OFA Workshop will offer a rich program covering a broad range of topics related to network deployment.

Get involved in this exciting, community-driven industry experience by answering OFA’s Call for Sessions. Recommended session topics range from RDMA in Commercial Environments to Data Intensive Computing & Analytics. However, alternate topics are welcome; OFA encourages topic submissions that aren’t included in the current list.

IBTA members are encouraged to share their vast RDMA technology expertise by submitting session proposals on advancements surrounding InfiniBand and RoCE technology. To submit a proposal, go to the OFA Workshop 2017 Call for Sessions webpage (https://openfabrics.org/index.php/call-for-sessions.html) and follow the simple instructions.

If you are not interested in submitting a session proposal but would like to attend the workshop, register today to take advantage of the Early Bird rate:

Registration Type Pricing

Early Bird (through Feb 13) $595

Regular $695

On Site $695

For additional registration and lodging information, visit the Workshop registration page.

Questions or comments? Contact press@openfabrics.org.

Bill Lee

Author: admin Categories: OpenFabrics Alliance Tags: