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Hoyeon Lee (SUSE), Taehee Yoo (LINE Investment Technologies)
At LPC 2025, we presented an early prototype for running XDP programs directly on an AMD GPU from within the Linux kernel, without CUDA, ROCm, or any userspace component in the data path.[1]
Since then, the project has evolved into knod, an in-kernel network offload device, and an RFC patch set has been posted.[2] knod uses the GPU as a kernel-managed packet-processing accelerator: the...
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Geliang Tang
Multipath TCP (MPTCP) enables a device to simultaneously utilize multiple network interfaces for a single connection, providing enhanced redundancy, resilience, and bandwidth aggregation. Currently, an increasing number of network applications are beginning to support MPTCP, and some of them, such as NVMe over MPTCP and web servers like lighttpd, require TLS for MPTCP. However, MPTCP has...
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Marek Behรบn
There are multiple kernel drivers which could benefit were it possible to somehow do coroutines in C. Coroutines would make these drivers easier to comprehend, extend with new code paths, and debug.
The most common use case lies in simplifying complex state machines. For example consider the main state machine
Go to contribution pagesfp_sm_main()indrivers/net/phy/sfp.c. Each invocation executes code for a... -
Pranjal Shrivastava, Mr Shivaji Kant
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High-performance storage environments increasingly rely on direct data movement between PCIe endpoints, such as NVMe Controller Memory Buffers (CMB) or BAR memory. Today, NFS relies on standard page references (get_page) and doesn't support pinning pages for DMA, making the subsystem pin-unaware. Furthermore, the legacy iterator APIs used in NFS are incapable of passing the required... -
Toshiaki Makita (NTT, Inc.)
Building a driver for a new NIC normally means writing a kernel module. Whether you upstream it or maintain it out of tree, it requires a lot of effort. Isn't there a lighter-weight approach?
This talk shows one way to write the driver logic in userspace, without writing a kernel module, while the device still shows up as a Linux network device like "eth0". This is possible with existing...
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Tarun Shekher
Identity-based micro-segmentation depends on building a complete graph of workload-to-workload communication. For TCP, this is tractable: connections have clear lifecycle events observable via sock_ops and inet_sock_set_state tracepoints, and conntrack entries persist long enough for user space collection. UDP has none of this, and in production Kubernetes environments, UDP is everywhere: DNS...
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Dragoศ Tฤtulea (NVIDIA Corporation)
Systems that treat devices as untrusted protect themselves using confidential computing memory protection. Linux uses swiotlb to handle the necessary buffer bouncing transparently to drivers. For high-performance NICs operating at scale, however, the overhead of allocating and managing bounce buffers can substantially exceed the cost of the memory copies themselves.
Receive queues create...
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Martin Karsten (University of Waterloo)
The Linux network stack is a performance-critical component of the Linux kernel that impacts service delivery, quality, and efficiency. Subtle changes might have far-reaching performance implications. In this presentation I describe an emerging project to build a reference setup for networking performance and efficiency experiments. The objectives for this project are twofold. The immediate...
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Ms Alice Mikityanska (Isovalent at Cisco)
BIG TCP is a kernel feature that allows aggregating SKBs bigger than 64k, aiming to reduce per-packet overhead for high-throughput network traffic. Until now, it has mostly been practical for direct-routing deployments. A large class of production environments, including Kubernetes+Cilium setups, relies on UDP-based overlay networks, such as VXLAN and GENEVE.
This talk will walk through the...
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Stefano Garzarella (Red Hat)
Several userspace VMMs emulate virtio-vsock devices entirely in userspace, and vhost-user-vsock provides a similar capability through the vhost-user protocol, to reduce the kernel attack surface or to run on platforms where vhost-vsock is not available. However, only the vhost-vsock kernel module, which emulates the virtio-vsock device in the host kernel, integrates directly with
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Raman Shukhau
As server platforms increasingly ship with multiple frontend NICs, there is a growing need to utilize all available network paths transparently โ without application changes. We propose a BPF-based approach that leverages cgroup hooks at connect() time to perform client-side path selection across multiple NICs, effectively implementing a form of TCP multipath at the host level. To avoid the...
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Dr Haiyang Zhang (Microsoft)
To optimize the PCI data path on the Azure MANA NIC, we implemented support for Completion Queue Entry, or CQE, coalescing. In the regular receive path, each packet can generate a separate CQE that must be processed by the driver, increasing interrupt pressure and CPU & PCI overhead. CQE coalescing reduces this cost by merging multiple CQEs into one aggregated completion that represents...
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