L. Iftode, J.P. Singh, and K. Li. Scope consistency: A bridge between release consistency and entry consistency. In Proceedings of the 8th Symposium on Parallel Algorithms and Architecture, June 1996.  Home/Search   Document Details and Download   Summary   Related Articles   Check

....consistency models can often be introduced without any or with only minor code changes. Relaxed consistency models have been extensively researched in the realm of Software Distributed Shared Memory (SW DSM) 13] 14] 15] and implemented in the form of relaxed consistency protocols [16] [17]. While latter ones are not applicable or necessary in HW DSM scenarios, the concept of relaxed consistency models can be applied in a rather straightforward way. The result for the programmer is a secure, global memory abstraction. III. LOCAL CONSISTENCY SCHEMES Based on these design ....

....when accessed outside a critical region, but rather between two barrier operations. Depending on a code s synchronization pattern, this can lead to fewer invalidations and improved performance. For the programmer, the result is a slightly more relaxed consistency model with two consistency scopes [17]. Due to the inherent separation between locks and barriers in most shared memory codes, however, it can be expected that the impact on the programming model will be negligible for most codes. This new scheme can be implemented by adding a second consistency flag to each cache line that mirrors ....

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L. Iftode, J. Singh, and L. Li, "Scope Consistency: A Bridge between Release Consistency and Entry Consistency," Theory of Computer Systems, vol. 31, pp. 451--473, 1998.

.... efficiently supported in software distributed shared memory (SDSM) systems [14] In an SDSM [11, 3, 10, 7] twodimensional distributions can cause a large amount of excess communication between nodes, even when using relaxed memory consistencies such as eager write shared [3] lazy write shared [10, 7, 8], or a hybrid [1] The primary problem is that two dimensional distributions force nodes to share data in two dimensions, but the data is organized in either a row or column major layout. Consequently, nodes share both rows and columns, meaning that every element in a page must be write shared, ....

L. Iftode, J. Pal Singh, and K. Li. Scope consistency: a bridge between release consistency and entry consistency. In Proceedings of the 8th Annual ACM Symposium on Parallel Algorithms and Architectures, June 1996.

....by looking at what other threads have read and written. The underlying protocol then flushes data only where needed and potentially only to those threads requiring that data. The release operation is a completely thread local operation requiring no interaction with main memory. Scope consistency [26] sends only the updates made within one (dynamic) scope to other threads. Updates made while in an outer scope remain cached. Again, the implementation is allowed to send updates to a variable early and an implementation is also allowed to prefetch over a scope entry point. Java supports a weakly ....

L. Iftode, J. P. Singh, and K. Li. Scope Consistency: A Bridge between Release Consistency and Entry Consistency. In Proceedings of the 8th ACM Annual Symposium on Parallel Algorithms and Architectures (SPAA'96), pages 277--287, Padua, Italy, 1996.

....the memory, which needs to be compensated in order to reach a stable and reliable environment for the user. This, however, can be easily accomplished by applying the formalism of relaxed consistency models, which are well known from the SW DSM domain [16, 18, 5] and research in this area (e.g. [13, 10, 21]) has shown that relaxed consistency models only lead to a minimal impact on the programmability. Hence, the ease of use is maintained despite the missing hardware coherency mechanisms. Non coherent systems, in coordination with an appropriate hardware coherency management, are therefore ....

....and retrieve remote data, an operation unnecessary in the approach discussed in this paper due to the assumed HW DSM capabilities. 4 Implementing Relaxed Consistency Models The work on SW DSM systems has lead to the definition and implementation of several different consistency models (e.g. [13, 10, 4]) Almost all of them, most prominently Release Consistency [13] can be implemented on non coherent hardware by combining the use of synchronization operations in user applications, like locks and barriers, with cache invalidations and write buffer flushes as introduced above. In the following, ....

[Article contains additional citation context not shown here]

L. Iftode, J. Singh, and L. Li. Scope Consistency: A Bridge between Release Consistency and Entry Consistency. Theory of Computer Systems, 31:451--473, 1998.

.... Herlihy s thesis work [19] LOOM [24] and the more recent pickling (serialization) of Java [32] Several software only S DSM systems have proposed that programmers explicitly identify the data to be modified in a critical section, either directly [23, 20] or by explicit [36, 4] or implicit [22] association with a synchronization object (lock) In contrast to systems that maintain coherence at the level of virtual memory pages, software only S DSM is less vulnerable to false sharing. In a similar vein, views in InterWeave relieve the system of the need to inform processes of updates to ....

L. Iftode, J. P. Singh, and K. Li. Scope Consistency: A Bridge Between Release Consistency and Entry Consistency. In Proc. of the 8th Annual ACM Symp. on Parallel Algorithms and Architectures, pages 451--473, Padua, Italy, June 1996.

....access after an acquire, instead of at the time of the acquire, which leads to a reduced number of messages transferred over the network when compared with the earlier version of the RC models. Two more variations of the RC model have been proposed: entry consistency [18] and scope consistency [19] models. Unlike the four RC models stated earlier, these models support somewhat different programming paradigm, in which the shared data in the program must be specifically associated with the synchronization objects. The entry consistency(EC) model guarantees that shared data becomes consistent ....

L. Iftode, J.P. Singh, and K. Li, "Scope consistency: A bridge between release consistency and entry consistency," in In Proc. 8th ACM Annual Symp. on Parallel Algorithms and Architectures, pages 277-287, Jun. 1996.

....the synchronization variables are subject to consistency. The main problem with this approach is that the user explicitly identifies the synchronization variables, the shared data that needs consistency, and the binding between the shared data and the synchronization variables. Scope consistency [60] tries to make the binding between shared data and synchronization variables implicit. The synchronization variables define scopes through which the memory is viewed, and an implicit association of data (pages) with scopes is achieved dynamically when a write access occurs inside the scope. In ....

....work is to make parallelism implicit by using a suitable data layout and by automatically ensuring consistency, with system support. The data layout is based on a general partitioning and a relaxed consistency scheme. Work on relaxed consistency originates in the virtual shared memory techniques [21, 60,61,72, 94]. One way of relaxing a strict consistency model is to ensure consistency only at synchronization points. In a software maintained consistency, the synchronization points can be either indicated by the user (programmer) or discovered by a compiler. The first option allows for high optimizations, ....

[Article contains additional citation context not shown here]

L. Iftode, J. P. Singh, and K. Li. Scope consistency: A bridge between release consistency and entry consistency. In Proc. of the 8th ACM Annual Symp. on Parallel Algorithms and Architectures (SPAA'96), pages 277--287, 1996.

....directories. Since our approach extends data coherency techniques, they are applicable to both hardware and software DSM systems. We are continuing to investigate ways to reduce the overhead of our approach. One possibility is to extend our approach to relaxed memory consistency models ( 3][5][7] in which case coherency is maintained only on locks. In addition, it is also possible to limit the amount of rollback caused by errors. We propose barriers (Global and Partial) with communicating processes such that all processes synchronizing on a barrier maintain consistent checkpoints ....

L. Iftode, et. al. "Scope consistency: A bridge between Release consistency and Entry consistency", Proc of the 8 th Annl ACM Symposium on Parallel Algorithms and Architectures. 1996.

....memory model that we used in [27, 26] I include the computation centric theory in this dissertation because it introduces concepts, such as constructibility, that I think will be important to other researchers who want to improve upon location consistency and BACKER. Most existing memory models [47, 3, 70, 64, 90, 20, 84] are expressed in terms of processors acting on memory. We call these memory models processor centric; the memory model specifies what happens when a processor performs some action on memory. In contrast, the philosophy of the computation centric theory is to separate the logical dependencies ....

L. IFTODE,J.P.SINGH, AND K. LI, Scope consistency: A bridge between release consistency and entry consistency, in Proceedings of the Eighth Annual ACM Symposium on Parallel Algorithms and Architectures (SPAA), Padua, Italy, June 1996, pp. 277--287.

....such a history mechanism that does not depend on program data sets or user interaction to improve performance. A implcmctatio of software scopc cosistcc l. In order to address the preb leto of false sharing commonly found in DSM systems, we introduce a software variation of scope consistency [23] that has a performance advantage for spe cific classes of parallel programs. Additionally, the use of scope consistency facilitates the use of multicast for those programs that make use of small, inde pendent critical sections. A DSM s stem for Widows NT. Brazes represents the first ....

....performance tuning techniques outlined in Section 2.4. 2.3 Software Scope Consistency Scope consistency was introduced as an enhancement to the SHRIMP AURC sys tem [22] and is a refinement of release consistency. A discussion of scope consistency and its hardware implementation can be found in [23]. Basically, scope consistency divides the execution of a program into scopes, and shared data is only guaranteed to be consistent at the end of a scope. Scopes are characterized as global or local scopes. Global scope delimiters include global synchronization events such as barriers. After a ....

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L. Iftode, J. Singh, and K. Li. Scope consistency: A bridge between release con- sistency and entry consistency. In The $th Amual A CM S!/mposium o Parallel Algorithms ad Architectures, June 1996.

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L. Iftode, J. P. Singh and K. Li. Scope Consistency: A Bridge between Release Consistency and Entry Consistency. In Proc. of the 8th ACM Annual Symposium on Parallel Algorithms and Architectures (SPAA'96), pages 277-287, June 1996.

....consistency (EC) model [7] which is even weaker and appears to be more efficient than LRC. Unfortunately, the programming interface associated with EC is not easy to use, as it requires explicit binding between synchronization variables (locks) and shared memory variables. Scope consistency (ScC) [8] has thus been proposed, aiming at good programmability and high performance. Figure 1. The distributed shared memory abstraction: Each processor sees a shared address space, delineated by the dashed outline, rather than a collection of distributed address spaces. Apart from the use of relaxed ....

....the lazy release consistency model, JIAJIA used the home based approach to realize the scope consistency model. This results in a more efficient implementation, since scope consistency produces less data propagation than lazy release consistency at lock acquire or barrier synchronization [8]. Later versions of JIAJIA also adopt the concept of home migration of shared memory pages, in order to achieve better adaptation to the memory access patterns of DSM applications. One of them is the home migration protocol implemented by JIAJIA V2.1 [15] This protocol shares the same objective ....

L. Iftode, J. P. Singh and K. Li. Scope Consistency: A Bridge between Release Consistency and Entry Consistency. In Proc. of the 8th ACM Annual Symposium on Parallel Algorithms and Architectures (SPAA'96), pages 277-287, June 1996.

No context found.

L. Iftode, J.P. Singh, and K. Li. Scope consistency: A bridge between release consistency and entry consistency. In Proceedings of the 8th Symposium on Parallel Algorithms and Architecture, June 1996.

No context found.

L. Iftode, J.P. Singh and K. Li: "Scope Consistency: A Bridge between Release Consistency and Entry Consistency", In Proc. of the 8th Annual ACM Symposium on Parallel Algorithms and Architectures, 1996.

No context found.

L. Iftode, J. Singh, and K. Li. Scope consistency: A bridge between release consistency and entry consistency. In Proc. of the 8th Annual ACM Symposium on Parallel Algorithms and Architectures, 1996.

No context found.

L. Iftode, J. Singh, and K. Li. Scope consistency: A bridge between release consistency and entry consistency. In Proc. of the 8th ACM Annual Symp. on Parallel Algorithms and Architectures (SPAA'96), pages 277--287, June 1996.

No context found.

L. Iftode, J. Singh, and K. Li. Scope consistency: A bridge between release consistency and entry consistency. In Proc. of the 8th ACM Annual Symp. on Parallel Algorithms and Architectures (SPAA'96), pages 277-287, June 1996.

No context found.

L. Iftode, J.P. Singh, and K. Li. Scope consistency: a bridge between release consistency and entry consistency. In Proceedings of the 8th Annual ACM Symposium on Parallel Algorithms and Architectures, June 1996.

No context found.

Iftode L., Singh J.P., Li K; Scope Consistency: A bridge between release consistency and entry consistency. Proceedings of the 8th ACM Annual Symposium on Parallel Algorithms and Architectures (SPAA'96), pp. 277-287, June, 1996.

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Liviu Iftode, Jaswinder Pal Singh, and Kai Li. Scope consistency: a bridge between release consistency and entry consistency. In Symposium on Parallel Algorithms and Architectures, pages 277-287, June 1996.

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Iftode, L., Singh, J. P., and Li, K. "Scope Consistency: A Bridge between Release Consistency and Entry Consistency" . Proc 8th ACM Annual Symp. on Parallel Algorithms and Architectures (SPAA'96), pages 277-287, June 1996.

No context found.

L. Iftode, J. Singh, and K. Li, "Scope Consistency: A Bridge between Release Consistency and Entry Consistency", In Proceedings of the 8th Annual ACM Symposium on Parallel Algorithms and Architectures, June 1996.

No context found.

Iftode, L. and Singh, J.P. and Li, K. Scope Consistency: A Bridge between Release Consistency and Entry Consistency. In Proceedings of the 8th Annual on ACM Symposium on Parallel Algorithms and Architectures, June 1996.

No context found.

L. Iftode, J. Singh, L. Li, Scope consistency: a bridge between release consistency and entry consistency, Theory Comput. Syst. 31 (1998) 451--473.

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Iftode, L., J.p. Singh, and K. Li. Scope Consistency: A Bridge between Release Consistency and Entry Consistency. in 8fi Annual ACM Symposium on Parallel Algorifims and Architectures. 1996.

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