Proceedings of the 29th ACM Symposium on Parallelism in Algorithms and Architectures最新文献

{"title":"Brief Announcement: Scheduling Parallelizable Jobs Online to Maximize Throughput","authors":"Kunal Agrawal, Jing Li, Kefu Lu, Benjamin Moseley","doi":"10.1145/3087556.3087590","DOIUrl":"https://doi.org/10.1145/3087556.3087590","url":null,"abstract":"We consider scheduling parallelizable jobs online to maximize the throughput or profit of the schedule. A set of n jobs arrive online and each job Ji has an associated function pi(t), the profit obtained for finishing job Ji at time t. Each job has its own arbitrary non-increasing profit function. We consider the case where each job is a parallel job that can be represented as a directed acyclic graph (DAG). We give the first non-trivial results for the profit scheduling problem for DAG jobs showing O(1)-competitive algorithms using resource augmentation.","PeriodicalId":162994,"journal":{"name":"Proceedings of the 29th ACM Symposium on Parallelism in Algorithms and Architectures","volume":"35 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128184352","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Improved Cover Time Bounds for the Coalescing-Branching Random Walk on Graphs","authors":"C. Cooper, T. Radzik, Nicolás Rivera","doi":"10.1145/3087556.3087564","DOIUrl":"https://doi.org/10.1145/3087556.3087564","url":null,"abstract":"We present improved bounds on the cover time of the coalescing-branching random walk process COBRA. The COBRA process, introduced in [Dutta et al., SPAA 2013], can be viewed as spreading a single item of information throughout an undirected graph in synchronised rounds. In each round, each vertex which has received the information in the previous round (possibly simultaneously from more than one neighbour and possibly not for the first time), 'pushes' the information to b randomly selected neighbours. The COBRA process is typically studied for integer branching rates b ge 2 (with the case b=1 corresponding to a random walk). The aim of the process is to propagate the information quickly, but with a limited number of transmissions per vertex per round. The cover time of COBRA is defined as the expected number of rounds until each vertex has received the information at least once. Our main results are a bound of O(m + (d_{max})^2log n) = O(n^2log n) on the COBRA cover time for an arbitrary connected graph with n vertices, m edges and the maximum vertex degree d_{max}, and a bound of O((r^2 + r/(1-lambda)) log n) for r-regular connected graphs with the second eigenvalue lambda. Our bounds improve the O(n^{11/4}log n) and ((r^4/phi^2)log^2 n) bounds shown in [Mitzenmacher et al., SPAA 2016], where phi is the conductance of the graph, and complement the O((1/(1-l))^3 log n) bound shown in [Cooper et al., PODC 2016]. We obtain our bounds by analysing the process called Biased Infection with Persistent Source (BIPS), which was introduced in [Cooper et al., PODC 2016] as a dual process for COBRA.","PeriodicalId":162994,"journal":{"name":"Proceedings of the 29th ACM Symposium on Parallelism in Algorithms and Architectures","volume":"6 11","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131520995","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Matrix Multiplication, a Little Faster","authors":"Elaye Karstadt, O. Schwartz","doi":"10.1145/3087556.3087579","DOIUrl":"https://doi.org/10.1145/3087556.3087579","url":null,"abstract":"Strassen's algorithm (1969) was the first sub-cubic matrix multiplication algorithm. Winograd (1971) improved its complexity by a constant factor. Many asymptotic improvements followed. Unfortunately, most of them have done so at the cost of very large, often gigantic, hidden constants. Consequently, Strassen-Winograd's O(nlog27) algorithm often outperforms other matrix multiplication algorithms for all feasible matrix dimensions. The leading coefficient of Strassen-Winograd's algorithm was believed to be optimal for matrix multiplication algorithms with 2x2 base case, due to a lower bound of Probert (1976). Surprisingly, we obtain a faster matrix multiplication algorithm, with the same base case size and asymptotic complexity as Strassen-Winograd's algorithm, but with the coefficient reduced from 6 to 5. To this end, we extend Bodrato's (2010) method for matrix squaring, and transform matrices to an alternative basis. We prove a generalization of Probert's lower bound that holds under change of basis, showing that for matrix multiplication algorithms with a 2x2 base case, the leading coefficient of our algorithm cannot be further reduced, hence optimal. We apply our technique to other Strassen-like algorithms, improving their arithmetic and communication costs by significant constant factors.","PeriodicalId":162994,"journal":{"name":"Proceedings of the 29th ACM Symposium on Parallelism in Algorithms and Architectures","volume":"278 2","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131958180","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Hand-Over-Hand Transactions with Precise Memory Reclamation","authors":"Tingzhe Zhou, Victor Luchangco, Michael F. Spear","doi":"10.1145/3087556.3087587","DOIUrl":"https://doi.org/10.1145/3087556.3087587","url":null,"abstract":"In this paper, we introduce revocable reservations, a transactional memory mechanism to reserve locations in one transaction and check whether they are unchanged in a subsequent transaction without preventing reserved locations from being reclaimed in the interim. We describe several implementations of revocable reservations, and show how to use revocable reservations to implement lists and trees with a transactional analog to hand-over-hand locking. Our evaluation of these data structures shows that revocable reservations allow precise and immediate reclamation within transactional data structures, without sacrificing scalability or introducing excessive latency.","PeriodicalId":162994,"journal":{"name":"Proceedings of the 29th ACM Symposium on Parallelism in Algorithms and Architectures","volume":"65 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133088360","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Session details: SESSION 7","authors":"M. Ghaffari","doi":"10.1145/3257331","DOIUrl":"https://doi.org/10.1145/3257331","url":null,"abstract":"","PeriodicalId":162994,"journal":{"name":"Proceedings of the 29th ACM Symposium on Parallelism in Algorithms and Architectures","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123304411","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Brief Announcement: Complete Visibility for Oblivious Robots in Linear Time","authors":"Gokarna Sharma, C. Busch, S. Mukhopadhyay","doi":"10.1145/3087556.3087591","DOIUrl":"https://doi.org/10.1145/3087556.3087591","url":null,"abstract":"We consider the distributed setting of $N$ autonomous mobile robots that operate in Look-Compute-Move cycles following the well-celebrated classic oblivious robots model. We study the fundamental problem where starting from an arbitrary initial configuration, N autonomous robots reposition themselves to a convex hull formation on the plane where each robot is visible to all others (the Complete Visibility problem). We assume obstructed visibility, where a robot cannot see another robot if a third robot is positioned between them on the straight line connecting them. We provide the first cO(N) time algorithm for this problem in the fully synchronous setting. Our contribution is a significant improvement over the runtime of the only previously known algorithm for this problem which has a lower bound of Omega(N^2). Our proposed algorithm is collision-free -- robots do not share positions and their paths do not cross.","PeriodicalId":162994,"journal":{"name":"Proceedings of the 29th ACM Symposium on Parallelism in Algorithms and Architectures","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122903848","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Lower Bounds in the Asymmetric External Memory Model","authors":"R. Jacob, Nodari Sitchinava","doi":"10.1145/3087556.3087583","DOIUrl":"https://doi.org/10.1145/3087556.3087583","url":null,"abstract":"Motivated by the asymmetric read and write costs of emerging non-volatile memory technologies, we study lower bounds for the problems of sorting, permuting and multiplying a sparse matrix by a dense vector in the asymmetric external memory model (AEM). Given an AEM with internal (symmetric) memory of size M, transfers between symmetric and asymmetric memory in blocks of size B and the ratio ω between write and read costs, we show Ω(min (N, ωN/B logω M/B N/B) lower bound for the cost of permuting N input elements. This lower bound also applies to the problem of sorting N elements. This proves that the existing sorting algorithms in the AEM model are optimal to within a constant factor for reasonable ranges of parameters N, M, B, and ω. We also show a lower bound of Ω(min {H, ω H/B logω M/B N/ max{δ ,M}}) for the cost of multiplying an N x N matrix with at most H= δ N non-empty entries by a vector with N elements.","PeriodicalId":162994,"journal":{"name":"Proceedings of the 29th ACM Symposium on Parallelism in Algorithms and Architectures","volume":"50 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114470811","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Session details: SESSION 3","authors":"Hossein Bateni","doi":"10.1145/3257326","DOIUrl":"https://doi.org/10.1145/3257326","url":null,"abstract":"","PeriodicalId":162994,"journal":{"name":"Proceedings of the 29th ACM Symposium on Parallelism in Algorithms and Architectures","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125425587","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Brief Announcement: A New Improved Bound for Coflow Scheduling","authors":"Mehrnoosh Shafiee, Javad Ghaderi","doi":"10.1145/3087556.3087598","DOIUrl":"https://doi.org/10.1145/3087556.3087598","url":null,"abstract":"Many data-parallel computing frameworks in today's datacenters consist of multiple computation and communication stages. A stage often cannot start or be completed unless all the required data pieces from the preceding stages are received. Coflow is a recently proposed networking abstraction to capture such communication patterns. We consider the problem of efficiently scheduling coflows with release dates in a shared datacenter network so as to minimize the total weighted completion time of coflows. This problem has been shown to be NP-complete, and several polynomial-time approximation algorithms have been recently proposed with provable performance guarantees. Our main result in this paper is a new polynomial-time approximation algorithm that improves the best prior known results. Specifically, we propose a deterministic algorithm with an approximation ratio of 5, which improves the prior best known ratio of 12. For the special case when all the coflows are released at time zero, we obtain an algorithm with an approximation ratio of $4$ which improves the prior best known ratio of 8.","PeriodicalId":162994,"journal":{"name":"Proceedings of the 29th ACM Symposium on Parallelism in Algorithms and Architectures","volume":"46 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127021822","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Proceedings of the 29th ACM Symposium on Parallelism in Algorithms and Architectures","authors":"C. Scheideler, M. Hajiaghayi","doi":"10.1145/3087556","DOIUrl":"https://doi.org/10.1145/3087556","url":null,"abstract":"It is our great pleasure to welcome you to the 29th ACM Symposium on Parallelism in Algorithms and Architectures -- SPAA 2017. The goal of SPAA is to develop a deeper understanding of parallelism in all its forms, bringing together the theory and practice of parallel computing. Over the last several years, the study of parallelism has significantly extended the state of the art in traditional areas of parallel computing but has also expanded to include various new models of parallel computation, new architectures, new techniques for managing parallelism, and new types of parallel systems -- in particular Spark, Hadoop, as well as MapReduce and its extension Flume. These increasingly important topics are also represented at SPAA this year. \u0000 \u0000The call for papers attracted 127 submissions. Out of these submissions, the program committee accepted 31 as regular papers (an acceptance rate of only 25%) and 14 as brief announcements (an acceptance rate of only 11%). The committee's decisions in accepting brief announcements were based on the perceived interest of these contributions, with the hope that extended versions of these announcements will be published later in other conferences or journals. \u0000 \u0000The keynote talks are given by Guy Blelloch (jointly with PODC) and Piotr Indyk. \u0000 \u0000The best paper award for SPAA 2017 is awarded to: \u0000Sepehr Assadi and Sanjeev Khanna: Randomized Composable Coresets for Matching an Vertex Cover \u0000Sudipto Guha, Yi Li and Qin Zhang: Distributed Partial Clustering \u0000 \u0000 \u0000 \u0000Assadi and Khanna consider the problems of finding maximum cardinality matchings and minimum vertex covers over randomized distributed inputs and achieve a constant approximation factor for maximum matching and an O(log n)-approximation factor for vertex cover. Guha, Li, and Zhang consider several fundamental and partial clustering problems such as k-center, k-median, and k-means with outliers in a distributed model, and provide algorithms with commu-nication sublinear of the input size.","PeriodicalId":162994,"journal":{"name":"Proceedings of the 29th ACM Symposium on Parallelism in Algorithms and Architectures","volume":"44 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128944700","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}