![]() As a consequence, the maximum packet rate between the two VMs is often limited by 2-5 Mpps. The emulation involves device-specific overhead - queue processing, format conversions, packet copies, address translations, etc. As a matter of facts, while netmap is fast on both the host (the VALE switch) and the guest (interaction between application and the emulated device), each packet still needs to be processed from the hypervisor, which needs to emulate the device model used in the guest (e.g. ![]() However, in a typical scenario with two communicating netmap applications running in different VMs (on the same host) connected through a VALE switch, the journey of a packet is still quite convoluted. The Virtual Ethernet (VALE) software switch, which supports scalable high performance local communication (over 20 Mpps between two switch ports), can then be used to connect together multiple VMs. virtio-net, Xen netfront/netback - allows netmap applications to run in the guest over fast paravirtualized I/O devices. Netmap support for various paravirtualized drivers - e.g. Several netmap extension have been developed to support virtualization. traditional socket API primarily comes from: (i) batching, since it is possible to send/receive hundreds of packets with a single system call, (ii) preallocation of packet buffers and memory mapping of those in the application address space. Rings are always accessed in the context of system calls and NIC interrups are used to notify applications about NIC processing completion. It exposes an hardware-independent API which allows userspace application to directly interact with NIC hardware rings, in order to receive and transmit Ethernet frames. Netmap is a framework for high performance network I/O. Extend bhyve to emulate the ptnet device model and interact with the netmap instance used by the hypervisor (estimated new code ~600 loc).Export a network interface to the FreeBSD guest kernel that allows ptnet to be used by the network stack, including virtio-net header support (estimated new code ~800 loc).Implement a ptnet driver for FreeBSD guests that is able to attach to netmap to support native netmap applications (estimated new code ~700 loc).Taking the above prototype as a reference, the following work is required: In this project I would like to implement ptnet for FreeBSD and bhyve, which do not currently allow TCP/IP traffic with such high performance. I have recently developed a prototype of ptnet, a new multi-ring paravirtualized device for Linux and QEMU/KVM that builds on ptnetmap to allow VMs to exchange TCP traffic at 20 Gbps, while still offering the same ptnetmap performance to native netmap applications. Moreover, ptnetmap was not able to support multi-ring netmap ports. Unfortunately, the original ptnetmap implementation was not able to exchange packets with the guest TCP/IP stack, it only supported guest applications running directly over netmap. Netmap passhthrough (ptnetmap) has been recently introduced on Linux/FreeBSD platforms, where QEMU-KVM/bhyve hypervisors allow VMs to exchange over 20 Mpps through VALE switches. Large speedups (5x and more) are also achieved on user-space Click and other packet forwarding applications using a libpcap emulation library running on top of netmap.High-performance TCP/IP networking for bhyve VMs using netmap passthrough This is more than 20 times faster than conventional APIs. In our prototype, a single core running at 900 MHz can send or receive 14.88 Mpps (the peak packet rate on 10 Gbit/s links). Netmap has been implemented in FreeBSD and Linux for several 1 and 10 Gbit/s network adapters. The novelty in our proposal is not only that we exceed the performance of most of previous work, but also that we provide an architecture that is tightly integrated with existing operating system primitives, not tied to specific hardware, and easy to use and maintain. Separately, some of these techniques have been used in the past. ![]() In building netmap, we identified and successfully reduced or removed three main packet processing costs: per-packet dynamic memory allocations, removed by preallocating resources system call overheads, amortized over large batches and memory copies, eliminated by sharing buffers and metadata between kernel and userspace, while still protecting access to device registers and other kernel memory areas. In this paper we present netmap, a novel framework that enables commodity operating systems to handle the millions of packets per seconds traversing 1.10 Gbit/s links, without requiring custom hardware or changes to applications. Many applications (routers, traffic monitors, firewalls, etc.) need to send and receive packets at line rate even on very fast links.
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