Fast Mutual Exclusion for Uniprocessors
Abstract
In this paper we describe restartable atomic sequences, an optimistic mechanism for implementing simple atomic operations (such as Test-and-Set) on a uniprocessor. A thread that is suspended within a restartable atomic sequence is resumed by the operating system at the beginning of the sequence, rather than at the point of suspension. This guarantees that the thread eventually executes the sequence atomically. A restartable atomic sequence has significantly less overhead than other software-based synchronization mechanisms, such as kernel emulation or software, reservation. Consequently, it is an attractive alternative for use on uniprocessors that do not support atomic operations. Even on processors that do support atomic operations in hardware, restartable atomic sequences can have lower overhead. We describe different implementations of restartable atomic sequences for the Mach 3.0 and Taos operating systems. These systems' thread management packages rely on atomic operations to implement higher-level mutual exclusion facilities. We show that improving the performance of low-level atomic operations, and therefore mutual exclusion mechanisms, improves application performance.
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 01, 1992
- Accession Number
- ADA261663
Entities
People
- Brian N. Bershad
- David D. Redell
- John R. Ellis
Organizations
- Carnegie Mellon University