netmap

netmap

相关论文目录：

1. 《netmap: a novel framework for fast packet I/O》
2. 《netmap: Memory Mapped Access To Network Devices》
3. 《Revisiting network i/o aPis: The netmap framework》
4. 《Transparent acceleration of software packet forwarding using netmap》
5. 链接：http://info.iet.unipi.it/~luigi/netmap/

《netmap: a novel framework for fast packet I/O》

netmap is a framework to reduce the cost of moving traffic between the hardware and the host stack.

The previous survey shows that most related proposals have identified, and tried to remove, the following high cost operations in packet processing: data copying, metadata management, and system call overhead..

Our framework, called netmap, is a system to give user space applications very fast access to network packets, both on the receive and the transmit side, and including those from/to the host stack.

由不足推出netmap

传统的数据包转发处理经常都是用套接字API或者libpacp。这些都涉及系统调用和内存复制成本。在内核中，设备驱动程序处理这些数据包需要经过一系列的动作。这是一个耗时较长的时间。有一个数据可以说明一点，

current per-core performance on standard OS is 0.5 Mpps for userspace apps, up to 1..2 Mpps for in-kernel apps, and poor scalability with number of cores

(内核应用程序的可扩展性很差。)

还有就是网卡NIC能够管理一些很少或者没有CPU干预的缓冲器的循环列表。但是操作系统没有很好的利用这些功能。

netmap

netmap is a framework to reduce the cost of moving traffic between the hardware and the host stack.

netmap可以直接在用户空间下实现完整的网络协议栈，可以绕过一些不必要的上下文切换和不需要的协议开销。

netmap解决的三个问题：

1. 减少动态申请/释放 内存的开销；
2. 减少系统调用的开销；
3. 减少内存拷贝的开销；

netmap用到的性能提高技术：

1. 内存映射

2. 批处理

3. 环形缓冲区队列

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实验结果:

netmap使用70..90CPU时钟周期去发送或者接受一个数据包，时间比标准API的10-20倍，而且有一个好的扩展性对于CPU核心数以及时钟频率。

netmap

定义：一种是高性能的应用层收发包框架。

起源：

研究方向：实现数据包的转发速率的提高

发起者：Luigi Rizzo∗ , Universita di Pisa, Italy

具体项目：

1、Luigi Rizzo, Marta Carbone, Gaetano Catalli, Transparent acceleration of software packet forwarding using netmap (Infocom 2012, March 2012). Describes how we ported OpenvSwitch and Click to netmap (with huge speedups);

描述了如何移植到OpenvSwitch并且通过netmap，有了巨大的速度上的提升。

2、Luigi Rizzo, Giuseppe Lettieri, VALE, a switched ethernet for virtual machines, ACM CoNEXT'2012, Nice, France, Dec.2012, describes a very fast software switch using netmap as communication API

VALE软件交换机是一个使用了Netmap作为他内核的一个单独模块。

时间点：Luigi Rizzo, Matteo Landi, netmap: memory mapped access to network devices, best poster award at SIGCOMM 2011, describes the idea and initial implementation.