Socket Swapping for efficient distributed communication between migrating processes MS Final Defense Praveen Ramanan 12 th Dec 2002

Introduction What is Process Migration? The mechanism of transferring a process between two machines during its execution What is Socket Migration? The mechanism of transferring one end of a live connection from one host to another without loss or interruption to the packet flow

Need for Socket Migration Lack of Network Socket Migration at the Operating System Level MOSIX, its importance with socket migration

MOSIX and its characteristics Software that can transform a Linux cluster of x86 based workstations and servers to run almost like an SMP Has the ability to distribute and redistribute the processes among the nodes

Process Migration in MOSIX User-level Kernel Link Layer User-level Kernel Link Layer Deputy Remote Local process A local process and a migrated process

Solution: Kernel Socket Swapping Processes in machine A and B Communicate through Sockets Process migrates to Machine C Process then communicates through C library SocketSwap is called After communication Communication is re-established between the processes A B C

Technologies/Tools Used User Mode Linux (UML) Aglets JNI (Java Native Interface)

Sockets OS interface that allow communication between two different processes on same or different machines Behaves much like a low-level file descriptor Identified by a host.port pair

System calls Entry points through which an active process obtain services from the kernel Distinction between user mode and kernel mode Context switch done by generating a software interrupt

Socket related System Calls Socket() Bind() Listen() Connect() Accept() Read() and Write() Close()

Socket Strucuture struct socket { socket_state state; unsigned long flags; struct proto_ops *ops; struct inode *inode; struct fasync_list *fasync_list; struct file *file; struct sock *sk; wait_queue_head_t wait; short type; unsigned char passcred; }

Writing the System Call Implemented in User Mode Linux, a safe secure way of running linux versions and linux processes

Why UML? UML is a virtual machine which runs linux inside linux Debugging and testing becomes easy Protects the main linux machine from abnormal crashes

Features of UML It has a fully functional kernel It has hardware support It has access to host file system It is completely configurable, allowing its memory, available devices to be specified

Mobile agents and aglets Have unique ability to transport themselves from one system to another Aglets are java objects that can move from one host to the other Aglets takes the program code as well as data during its movement

Testing the System Call through aglets and JNI Aglets are made to communicate through a C library (C library uses sockets) through JNI During communication, aglets are made to move from one machine to another System call is called and the socket is swapped The communication of the moved aglet is then established with the swapped socket

4.Local C library communicates with C library of the remote machine. 4 2.Aglet B moves from one machine to another. 2 3.AgletB Contacts the HaveMoved() of the local C library 3 1. Aglets A and B are communicating within the same machine thru Send and Recv Fns of C library API 1 5.system call swaps the socket 5

6.New Communication is established between the processes after socket swap. 6

Results (Data Size:400MB) Latency(sec)BandWidth(Mbps) Mosix Normal Linux TCP UserModeLinux SocketSwap

Questions?

Acknowledgements Dr Daniel Andresen Dr Gurdip Singh Dr Mitchell Neilsen