UNSW Computer Science and Engineering Technical Report no. UNSW-CSE-TR-9704 (23 pages: file 9704.pdf) Title: Implementation and Performance of the Mungi Single-Address-Space Operating System Authors: Gernot Heiser, Kevin Elphinstone, Jerry Vochteloo, Stephen Russell Department of Computer Systems School of Computer Science and Engineering University of New South Wales Sydney 2052 Australia Jochen Liedtke IBM T. J. Watson Research Center 30 Saw Mill River Road Hawthorne, NY 10532, USA E-mail: {gernot,jerry,kevine,smr}@cse.unsw.edu.au jochen@watson.ibm.com Abstract: Single-address-space operating systems (SASOS) are an attractive model for making the best use of the wide address space provided by the latest generations of microprocessors. SASOS remove the address space borders which make data sharing between processes difficult and expensive in traditional operating systems. This offers the potential of significant performance advantages for applications where sharing is important, such as object-oriented databases or persistent programming systems. Previously published SASOS were not able to demonstrate these performance advantages. We have built the Mungi system to show that these advantages can indeed be realized. Mungi is a very ``pure'' SASOS, featuring an unintrusive protection model based on sparse capabilities, a fast protected procedure call mechanism, and uses virtual memory as the exclusive inter-process communication mechanism, as well as for I/O. We believe this simplicity of our model makes it easy to implement it efficiently on conventional architectures. Our realization of Mungi for the MIPS R4600 64-bit microprocessor is presented, which is based on our implementation of the L4 microkernel. Mungi is shown to outperform a well-tuned commercial operating system in several important aspects, such as task creation and inter-process communications, and on the OO1 object-oriented database benchmark. This demonstrates clearly that the SASOS concept is viable, and that a well-designed microkernel is an excellent base on which to build high-performance operating systems. ftp://ftp.cse.unsw.edu.au/pub/doc/papers/UNSW/9704.pdf