Chelsio Communications Chelsio T4 Guía de usuario descargar pdf (Pagina 78)

Chapter V. WD-UDP

4. Software/Driver Configuration and Fine-tuning

4.1. Accelerating UDP Socket communications

The libcxgb4_sock library is a LD_PRELOAD-able library that accelerates UDP Socket

communications transparently and without recompilation of the user application. This section

describes how to use libcxgb4_sock.

By preloading libcxgb4_sock, all sockets created by the application are intercepted and possibly



transmitted or received via HW queues allocated specifically for the accelerated endpoint,

bypassing the kernel, the host networking stack and sockets framework, and enabling ultra-low

latency and high bandwidth utilization.

Due to HW resource limitations, only a small number of queues can be allocated for UDP

acceleration. Therefore only performance critical UDP applications should use libcxgb4_sock.

Only 64 IPv4 UDP sockets / 28 IPv6 UDP Sockets can be accelerated per Chelsio T4

device used.

4.1.1. Application Requirements

Certain application behavior is not supported by libcxb4_sock in this release. If your application

does any of the following, it will not work with libcxgb4_sock:

Calling fork() after creating UDP sockets and using the UDP socket in the child process.

Using multiple threads on a single UDP socket without serialization. For instance, having

one thread sending concurrently with another thread receiving. If your application does this,

you need to serialize these paths with a spin or mutex lock.

Only 1 UDP endpoint is allowed to bind to a given port per host. So if you have multiple

processes on the same host binding to the same UDP port number, you cannot use

libcxgb4_sock.

Applications must have root privileges to use libcxgb4_sock.

Applications requiring bonded T4 interfaces are not currently supported.

The performance benefit observed with       

behavior. While all UDP IO is handled properly, only certain datagrams are accelerated. Non

accelerated IO is handled by libcxgb4_sock via the host networking stack seamlessly. Both

Unicast and Multicast datagrams can be accelerated, but the datagrams must meet the

following criteria:

Non fragmented. In other words, they fit in a single IP datagram that is <= the T4 device

MTU.

Routed through the T4 acceleration device. If the ingress datagram arrives via a device

other than the T4 acceleration device, then it will not utilize the acceleration path. On

1 2 ... 73 74 75 76 77 78 79 80 81 82 83 ... 373 374

Sin comentarios

Chelsio Communications Chelsio T4 Guía de usuario Pagina 78