Jochen Liedtke
Encyclopedia
Jochen Liedtke was a German
computer scientist
, noted for his work on microkernel
s, especially the creation of the L4 microkernel family
.
Liedtke's work on the ELAN programming language in the 1970s led him to create Eumel
, an innovative run-time environment
for Elan. In 1984, he joined the GMD (, or Society for Mathematics and Information technology, which is now a part of the Fraunhofer Society
) and began working on L3, a successor to Eumel. At a time when microkernels were losing favour because of the relatively high cost of message passing
, he demonstrated that careful design and implementation could drastically reduce IPC
costs. He also proposed using a hierarchy of external pagers (page fault
handlers), an important feature of modern microkernels.
Liedtke also worked on computer architecture
, inventing guarded page table
s as a means of implementing a sparsely-mapped 64-bit address space. In 1996, Liedtke completed a PhD on guarded page tables at the Technical University of Berlin
. He then joined the Thomas J. Watson Research Center
where he began work on L4. In 1999, he became a professor at the University of Karlsruhe. He died in a car accident in 2001.
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...
computer scientist
Computer scientist
A computer scientist is a scientist who has acquired knowledge of computer science, the study of the theoretical foundations of information and computation and their application in computer systems....
, noted for his work on microkernel
Microkernel
In computer science, a microkernel is the near-minimum amount of software that can provide the mechanisms needed to implement an operating system . These mechanisms include low-level address space management, thread management, and inter-process communication...
s, especially the creation of the L4 microkernel family
L4 microkernel family
L4 is a family of second-generation microkernels, generally used to implement Unix-like operating systems, but also used in a variety of other systems.L4 was a response to the poor performance of earlier microkernel-base operating systems...
.
Liedtke's work on the ELAN programming language in the 1970s led him to create Eumel
Eumel
Eumel is an operating system which began as a run-time environment for the ELAN programming language. It was created in 1979 by Jochen Liedtke at theUniversity of Bielefeld...
, an innovative run-time environment
Run-time system
A run-time system is a software component designed to support the execution of computer programs written in some computer language...
for Elan. In 1984, he joined the GMD (, or Society for Mathematics and Information technology, which is now a part of the Fraunhofer Society
Fraunhofer Society
The Fraunhofer Society is a German research organization with 60 institutes spread throughout Germany, each focusing on different fields of applied science . It employs around 18,000, mainly scientists and engineers, with an annual research budget of about €1.65 billion...
) and began working on L3, a successor to Eumel. At a time when microkernels were losing favour because of the relatively high cost of message passing
Message passing
Message passing in computer science is a form of communication used in parallel computing, object-oriented programming, and interprocess communication. In this model, processes or objects can send and receive messages to other processes...
, he demonstrated that careful design and implementation could drastically reduce IPC
Inter-process communication
In computing, Inter-process communication is a set of methods for the exchange of data among multiple threads in one or more processes. Processes may be running on one or more computers connected by a network. IPC methods are divided into methods for message passing, synchronization, shared...
costs. He also proposed using a hierarchy of external pagers (page fault
Page fault
A page fault is a trap to the software raised by the hardware when a program accesses a page that is mapped in the virtual address space, but not loaded in physical memory. In the typical case the operating system tries to handle the page fault by making the required page accessible at a location...
handlers), an important feature of modern microkernels.
Liedtke also worked on computer architecture
Computer architecture
In computer science and engineering, computer architecture is the practical art of selecting and interconnecting hardware components to create computers that meet functional, performance and cost goals and the formal modelling of those systems....
, inventing guarded page table
Page table
A page table is the data structure used by a virtual memory system in a computer operating system to store the mapping between virtual addresses and physical addresses. Virtual addresses are those unique to the accessing process...
s as a means of implementing a sparsely-mapped 64-bit address space. In 1996, Liedtke completed a PhD on guarded page tables at the Technical University of Berlin
Technical University of Berlin
The Technische Universität Berlin is a research university located in Berlin, Germany. Translating the name into English is discouraged by the university, however paraphrasing as Berlin Institute of Technology is recommended by the university if necessary .The TU Berlin was founded...
. He then joined the Thomas J. Watson Research Center
Thomas J. Watson Research Center
The Thomas J. Watson Research Center is the headquarters for the IBM Research Division.The center is on three sites, with the main laboratory in Yorktown Heights, New York, 38 miles north of New York City, a building in Hawthorne, New York, and offices in Cambridge, Massachusetts.- Overview :The...
where he began work on L4. In 1999, he became a professor at the University of Karlsruhe. He died in a car accident in 2001.
External links
- In Memoriam Jochen Liedtke (1953 - 2001)
- List of publications related to microkernels