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A Fast Mutual Exclusion Algorithm
, 1986
"... A new solution to the mutual exclusion problem is presented that, in the absence of contention, requires only seven memory accesses. It assumes atomic reads and atomic writes to shared registers. Capsule Review To build a useful computing system from a collection of processors that communicate by ..."
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Cited by 219 (6 self)
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A new solution to the mutual exclusion problem is presented that, in the absence of contention, requires only seven memory accesses. It assumes atomic reads and atomic writes to shared registers. Capsule Review To build a useful computing system from a collection of processors that communicate by sharing memory, but lack any atomic operation more complex than a memory read or write, it is necessary to implement mutual exclusion using only these operations. Solutions to this problem have been known for twenty years, but they are linear in the number of processors. Lamport presents a new algorithm which takes constant time (five writes and two reads) in the absence of contention, which is the normal case. To achieve this performance it sacrifices fairness, which is probably unimportant in practical applications. The paper gives an informal argument that the algorithm's performance in the absence of contention is optimal, and a fairly formal proof of safety and freedom from deadlock, u...
A First Come First Served Mutual Exclusion Algorithm With Small Communication Variables
 ACM Transactions on Programming Languages and Systems
, 1991
"... We present an algorithm for the mutual exclusion problem that satisfies the "first come first served" property and requires only five shared bits per participant. The algorithm works in a model of concurrency that does not assume atomic operations. August 26, 1991 i 1. Introduction Mutual exclusio ..."
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Cited by 13 (1 self)
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We present an algorithm for the mutual exclusion problem that satisfies the "first come first served" property and requires only five shared bits per participant. The algorithm works in a model of concurrency that does not assume atomic operations. August 26, 1991 i 1. Introduction Mutual exclusion is a basic and classic synchronisation problem. Informally it can be formulated as follows. We have a collection of N processes each having the structure illustrated in Figure 1.1. repeat NCS Trying Protocol CS Exit Protocol forever Figure 1.1: Mutual exclusion problem Each process iterates repeatedly through a noncritical section (NCS) and a critical section (CS). The problem is to design a Trying Protocol and and Exit Protocol which surround the critical section and synchronise access to it in the following sense: Mutual Exclusion: No two processes should ever be inside their critical sections at the same time. Deadlock Freedom: A set of processes wishing to enter the critical sec...
Fischer's Protocol in Timed Process Algebra
, 1994
"... Timed algebraic process theories can be developed with quite different purposes in mind. One can aim for theoretical results about the theory itself (completeness, expressiveness, decidability), or one can aim for practical applicability to nontrivial protocols. Unfortunately, these aims do not go ..."
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Cited by 7 (2 self)
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Timed algebraic process theories can be developed with quite different purposes in mind. One can aim for theoretical results about the theory itself (completeness, expressiveness, decidability), or one can aim for practical applicability to nontrivial protocols. Unfortunately, these aims do not go well together. In this paper we take two theories, which are probably of the first kind, and try to find out how well suited they are for practical verifications. We verify Fischer's protocol for mutual exclusion in the settings of discretetime process algebra (ACP dt ) and realtime process algebra (ACP ur ). We do this by transforming the recursive specification into an equivalent linear specification, and then dividing out the maximal bisimulation relation. The required mutual exclusion result can then be found by reasoning about the obtained process graph. Finally, we consider the ease of the verification, and ways to adapt the theory to make it more practical. It will turn out that the...
Mutual Exclusion Using Invisible Reads and Writes
 In Proceedings of the 18th Annual Allerton Conference on Communication, Control, and Computing
, 1980
"... The shared space (the number of distinct values taken on by the set of shared variables) requirements of Dijkstra's original mutual exclusion problem are examined. It is shown that 2 shared states are necessary and sufficient to solve the problem of deadlockfree mutual exclusion for N processes usi ..."
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The shared space (the number of distinct values taken on by the set of shared variables) requirements of Dijkstra's original mutual exclusion problem are examined. It is shown that 2 shared states are necessary and sufficient to solve the problem of deadlockfree mutual exclusion for N processes using only individual reads and writes of shared variables for communication.
"Writers"
"... The problem of the mutual exclusion of several independent processes from simultaneous access to a "critical section " is discussed for the case where there are two distinct classes of processes known as "readers" and "writers. " The "readers " may share the section with each other, but the "writers ..."
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The problem of the mutual exclusion of several independent processes from simultaneous access to a "critical section " is discussed for the case where there are two distinct classes of processes known as "readers" and "writers. " The "readers " may share the section with each other, but the "writers " must have exclusive access. Two solutions are presented: one for the case where we wish minimum delay for the readers; the other for the case where we wish writing to take place as early as possible. Key Words and Phrases: mutual exclusion, critical section, shared access to resources
A New Solution to Lamport's Concurrent Programming . . .
, 1983
"... A new solution to the concurrent programming control (mutual exclusion) problem that is immune to process failures and restarts is presented. The algorithm uses just four values of shared memory per process, which is within one value of the known lower bound. The algorithm is implemented using two b ..."
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A new solution to the concurrent programming control (mutual exclusion) problem that is immune to process failures and restarts is presented. The algorithm uses just four values of shared memory per process, which is within one value of the known lower bound. The algorithm is implemented using two binary variables that make it immune to read errors occurring during writes, that is, "flickering bits."
A Fast Mutual Exclusion Algorithm Leslie Lamport
, 1985
"... of fee is granted for nonprofit educational and research purposes provided ..."
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of fee is granted for nonprofit educational and research purposes provided