cse221: paper evals

Octavian Luca (oluca@cs.ucsd.edu)
Tue, 6 Jun 2000 00:31:04 -0700 (PDT)

Extensibility, Safety and Performance in SPIN OS

This paper describes the extensible operating system SPIN. It provides
and extension infrastructure and a core set of extensible services meant
to allow applications to safely change the operating system's interface
and implementation. The goal of these extensions is to allow applications
to specialize the underlying OS to acheive desirable performance and
functionality. This work differes from previous work in it's focus on
goals of extensibility, safety, and good performance.

To achieve the previously mentioned goals, Spin uses four techniques:
co-location, enforced modularity, logical protection domains and dynamic
call binding. Of note is the reliance on the language features such as
type safety, automated storage management, objects, and threads provided
by the Modula-3 programming language that was used to implement Spin. The
OS uses extension models for determining the ease, transparency and
efficiency with which extensions can be applied. Spin also provides a set
of core services for managing memory and processor resources.

The researchers illustrate the benefits of their approach over previous
works using a varied set of benchmarks for measuring protected
communication, thread management, and virtual memory. The result tables
clearly show the merit of their new approach. This paper shows yet
another interesting aspect of OSes and seems to suggest that this topic
has great growth potential due to constant demands for improved


This paper discusses the design ideas that make up of Exokernel, an
operating system architecture that provides application-level management
of physical resources. The main goal of this system is the removal of
limits on performance, flexibility, and functionality of applications by
securely exporting all hardware resources through a low-level interface to
untrusted library OSes. The design philosophy of this system is based on
one simple observation: that the lower the level of a primitive, the more
efficiently it can be implemented. To export resources securely the
designers used secure bindings, visible resource revocation and an abort

Similar to the previous paper, the researchers provided various
comparisons to illustrate the performance advantage of their system over
previous work. Furthermore, they instantiate their ideas in Aegis, an
exokernel. Related work in thid area was used to highlight benefits of
this system.