Abstract We present an adaptive algorithm for N-process mutual exclusion under read/write atomicity in which all busy waiting is by local spinning. In our algorithm, each process p performs O(k) remote memory references to enter and exit its critical section, where k is the maximum "point contention " experienced by p. The space complexity of our algorithm is \Theta (N), which is clearly optimal. Our algorithm is the first mutual exclusion algorithm under read/write atomicity that is adaptive when time complexity is measured by counting remote memory references. All previous so-called adaptive mutual exclusion algorithms employ busy-waiting loops that can generate an unbounded number of remote memory references. Thus, they have unbounded time complexity under this measure.

In 1993, Yang and Anderson presented an N-process algorithm for mutual exclusion under read/write atomicity that has \Theta(log N) time complexity, where "time" is measured by counting remote memory references. In this algorithm, instances of a two-process mutual exclusion algorithm are embedded within a binary arbitration tree. In the two-process algorithm that was used, all busy-waiting is done by "local spinning." Performance studies presented by Yang and Anderson showed that their N-process algorithm exhibits scalable performance under heavy contention. One drawback of using an arbitration tree, however, is that each process is required to perform \Theta(log N) remote memory operations even when there is no contention. To remedy this problem, Yang and Anderson presented a variant of their algorithm that includes a "fast-path" mechanism that allows the arbitration tree to be bypassed in the absence of contention. This algorithm has the desirable property that contention-fre...

this paper we were able to define and implement a variant of the Moir-Anderson splitter that does not have all the properties that their splitter has but on the other hand, has an adaptive and long-lived implementation. Furthermore, we use this splitter as a building block in constructions other than a grid (for example a row of splitters or a tree of splitters) and in this way implement diverse applications such as mutual exclusion and optimal name space renaming

Mutual exclusion is a fundamental distributed coordination problem. Shared-memory mutual exclusion research focuses on local-spin algorithms and uses the remote memory references (RMRs) metric. A recent proof [9] established an Ω(log N) lower bound on the number of RMRs incurred by processes as they enter and exit the critical section, matching an upper bound by Yang and Anderson [18]. Both these bounds apply for algorithms that only use read and write operations. The lower bound of [9] only holds for deterministic algorithms, however; the question of whether randomized mutual exclusion algorithms, using reads and writes only, can achieve sub-logarithmic expected RMR complexity remained open. This paper answers this question in the affirmative. We present two strong-adversary [8] randomized local-spin mutual exclusion algorithms. In both algorithms, processes incur O(log N / log log N) expected RMRs per passage in every execution. Our first algorithm has sub-optimal worstcase RMR complexity of O ( (log N / log log N) 2). Our second algorithm is a variant of the first that can be combined with a deterministic algorithm, such as [18], to obtain O(log N) worst-case RMR complexity. The combined algorithm thus achieves sub-logarithmic expected RMR complexity while maintaining optimal worst-case RMR complexity. Our upper bounds apply for both the cache coherent (CC) and the distributed shared memory (DSM) models.

this paper. Motivated by their first work Moir and Anderson developed renaming algorithms, in the read/write model, when such a bound on the maximum number of processes is known in advance. This led to a sequence of works on the renaming problem in this model [MA95, MG96, BGHM95] that lead to a long-lived (2K \Gamma 1)-renaming algorithm with O(K ) step complexity and O(K space complexity [Moi98]. These works employed various variants of the splitter building block which is a descendant of Lamport's adaptive mutual exclusion algorithm, however the last one [Moi98] depends on an additional work which is the first long-lived renaming algorithm by Burns and Peterson [BP89]

Abstract Mutual exclusion is a fundamental distributed coordination problem. Shared-memory mutual exclusion research focuses on local-spin algorithms and uses the remote memory references (RMRs) metric. Attiya, Hendler, and Woelfel (40th STOC, 2008) established an �(log N) lower bound on the number of RMRs incurred by processes as they enter and exit the critical section, where N is the number of processes in the system. This matches the upper bound of Yang and Anderson (Distrib. Comput. 9(1):51–60, 1995). The upper and lower bounds apply for algorithms that only use read and write operations. The lower bound of Attiya et al., however, only holds for deterministic algorithms. The question of whether randomized mutual exclusion algorithms, using reads and writes only, can achieve sub-logarithmic expected RMR complexity remained open. We answer this question in the affirmative by presenting starvation-free randomized mutual exclusion algorithms for the cache coherent (CC) and the distributed shared memory (DSM) model that have sub-logarithmic expected RMR complexity against the strong adversary. More specifically, each process incurs an expected number of O(log N / log log N) RMRs per passage through the entry and exit sections, while in the worst case the number of RMRs is O(log N). P. Woelfel was supported by NSERC.

60dB 4.20 512 96 ETSI-A ETSI-A ETSI-1 60dB 4.20 1536 512 AWGN-140 AWGN-140 Draft Recommendation G.992.2 140 14 T1.601 #9 1536kbps 256kbps 49 Annex A G.992.2 15 T1.601 #9 1536kbps 256kbps 24 DSL 16 Shortened T1.601#7 1536kbps 256kbps 24 HDSL Table 47. Extended Reach Test Cases NOTE1: A goal of future enhancements of this Recommendation is to make the "Extended Reach Cases" mandatory. NOTE2: Performance levels do not reflect the effect of customer premise wiring, which is expected to reduce data rate.G.992.2G.992.2G.992.2 Draft Recommendation G.992.2 139 ANNEX D D.1 System Performance for North America All test loops specified in this section shall be used for G.992.2 and testing shall confirm to the following: . No power cutback on upstream transmitter. . Margin=4 dB . BER=10 -7 . Background noise = -140 dBm/Hz . Rates, except where noted,

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Abstract — This paper presents a new algorithm for mutual exclusion in which each passage through the critical section costs amortized O(log 2 logn) RMRs with high probability. The algorithm operates in a standard asynchronous, local spinning, sharedmemory model with an oblivious adversary. It guarantees that every process enters the critical section with high probability. The algorithm achieves its efficient performance by exploiting a connection between mutual exclusion and approximate counting. 1.