Project 4a - Design and implementation of a fiber loop buffer for an edge server

Create an implementation that handles multimedia (video on demand) on a Linux-based system

Team Members

Name	Roll No.	e-mail	Contact
Suhas Hegde A	MT2009001	suhas.hegde@iiitb.net	9945131571
Vivek Kumar Singh	MT2009146	vivekkumar.singh@iiitb.net	9886317184
Naveen Kumar V	MT2009150	naveenkumar.v@iiitb.net	9036590977
Uday kamal R	MT2009113	udaykamal.r@iiitb.net	9243824060

Introduction

Video servers play a major role in video on demand systems and form one of the critical components of the system, hence improving the perfomace of the server is ultimately the improvement for the entire system. In the project the I/O performance of the video servers is focused on live555 Media server.

Live555 Server : http://www.live555.com/mediaServer/

Gap Analysis

In order to solve multiple data copy issue, the linux kernel (2.6 and above) provides “sendfile” system call to implement “zero copy method” over TCP sockets. The media streaming servers like “live 555” uses “read” and “write” system calls to perform the data transfer from disk to socket buffer. So, we have planned to make the following changes: • Write a system call sendfile_UDP() equivalent to sendfile which can work for UDP sockets over a RTP connection. • Make use of sendfile_UDP() call to perform read operation on the “Live 555” media server.

Existing System

Multiple copy operations takes place internally in the system.
- They are as follows…
  - Hard drive to the kernel buffer (DMA copy)
  - Kernel buffer to the user buffer(CPU copy)
  - User buffer to the socket buffer(CPU copy)
  - Socket buffer to protocol engine(DMA copy)
This is further worst for the Video/Streaming data.
Though the network infrastructures support high speed data transfer rate, the utilization and smart use of the same is limited by the above process over heads.

Sendto() + read() vs Sendfile()

Advantages of Using the sendfile() system call

Implemented Using Zero-Copy Method
Better CPU Utilization

Integration of Sendfile() into the live555 server

Various classes were identified and modified to support sendfile() in the media server.

Groupsock
GroupsockHelper
RTPInterface
RTPSink
MultiFramedRTPSink
Socket

Deliverables

Demo of working Live 555 media server implemented using Zero Copy method with help of senfile_UDP() system call for MP3 media streaming.

To download,click here