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Abstract - Technical Program - OSDI 99
Tornado: Maximizing Locality and Concurrency in a Shared Memory Multiprocessor Operating System
Ben Gamsa,University of Toronto
Orran Krieger, IBM T.J. Watson Research Center
Jonathan Appavoo, Michael Stumm, University of Toronto
Abstract
We describe the design and implementation of Tornado, a new operating
system designed from the ground up specifically for today's shared
memory multiprocessors. The need for improved locality in the
operating system is growing as multiprocessor hardware evolves,
increasing the costs for cache misses and sharing, and adding
complications due to NUMAness. Tornado is optimized so that locality
and independence in application requests for operating system
services--whether from multiple sequential applications or a single
parallel application--are mapped onto locality and independence in the
servicing of these requests in the kernel and system servers. By
contrast, previous shared memory multiprocessor operating systems all
evolved from designs constructed at a time when sharing costs were
low, memory latency was low and uniform, and caches were small; for
these systems, concurrency was the main performance concern and
locality was not an important issue. Tornado achieves this locality
by starting with an object-oriented structure, where every virtual and
physical resource is represented by an independent object. Locality,
as well as concurrency, is further enhanced with the introduction of
three key innovations: (i) clustered objects that
support the partitioning of contended objects across processors,
(ii) a protected procedure call facility that
preserves the locality and concurrency of IPC's, and
(iii) a new locking strategy that allows all locking to be
encapsulated within the objects being protected and greatly simplifies
the overall locking protocols. As a result of these techniques,
Tornado has far better performance characteristics, particularly for
multithreaded applications, than existing commercial operating
systems. Tornado has been fully implemented and runs both on Toronto's
NUMAchine hardware and on the SimOS simulator.
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