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Evaluation of Proposal 9905-2 PAMP
Categorized and Specialized Caching for SMP's
Hagersten

This proposal aims to incorporate selective caching techniques into a commodity SMP architecture, with the goal of using commodity SMPs instead of customized processors in environments with large data sets and real-time needs like telephone switches. The project will be performed in close collaboration with architects at Ericsson, who have expertise in the design of customized processors for this area.

This is a promising proposal. The overall idea---namely, making (hopefully) small adjustments to commodity SMPs so that they can be used effectively in such real-time applications---is a good one to pursue since it may lead to the leveraging of the commodity performance curve and investment in this important application area. The team seems very appropriate: the Ericsson collaborators have expertise in custom-processor design and in the applications, as well as access to appropriate workloads to drive the design and evaluation, and Prof. Hagersten is an internationally-recognized expert in the design of commodity-based architectures and systems with substantial industrial experience in both this area as well as real-time systems (at Ericsson). In addition to designing successful systems in industry, he has made many valuable contributions to computer architecture research as well.

The weakness of the proposal is in its lack of specificity. Customized caching techniques have been proposed for general-purpose computing and for special purpose computing for quite some time, as the proposal recognizes. While it is natural to see it being effective for special-purpose systems (e.g. media and streaming applications), the case for general-purpose systems has not appeared to justify the hardware complexity and intervention in commodity systems. The key strength of this proposal is its aim to target changes to commodity systems to make them more appropriate for this environment. However, the challenge is that these are general-purpose systems that are used in many more environments than real-time ones, so the changes must indeed be small enough to be acceptable and important enough in terms of performance improvement to influence the commodity industry. The proposal does not point toward any specific novel techniques toward this goal. While this is presumably the task of the research, I like to see some key ideas or directions in a proposal.

I recommend funding the proposal based on the strengths and experience of the personnel and the overall goal it aims to pursue.

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Evaluation of Proposal 9905-4 PAMP
Software Distributed Shared Memory-- New Applications and Scalability
Brorsson

This proposal aims to study three major areas: (i) the design of software distributed shared memory (S-DSM) systems for emerging web server and database applications, (ii) the design of S-DSM for embedded systems in surveillance applications, and (iii) the scaling of these systems.

The first area is an increasingly relevant area of study. However, the authors do not make a strong case for the importance of S-DSM in such systems. Key aspects of web servers, perhaps more important than performance optimizations, are availability and dealing with faults. It is arguable that these are easier to achieve with message passing than with a shared address space, and it is not clear so far that web servers are complex enough in their treatment of data to argue strongly for a shared address space. This lack of motivation can be attributed to length restrictions in the proposal, but it would have been good to have seen a stronger case made.

The third area, scalability of S-DSM systems, is important. The authors have been doing research in S-DSM systems, so they should be qualified to do this research.

The second area, S-DSM systems for embedded systems, is one that I did not understand fully from the proposal. It was not clear what new issues arise for S-DSM from the fact that embedded systems are being used, or even whether the S-DSM is being used across the "sensor" nodes or only on the database server (I assume the former). Is it simply that surveillance is a new application that is appropriate for S-DSM, or that somehow the embedded nature of the processors raises new issues. Studying new applications for systems is good. However, if the case is being made for new research issues, they are not articulated.

Overall, this proposal seeks to do research in generally important areas, so good things may emerge. Its negative is that it does not make its case very strongly or present many new ideas.

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ARTES: 9905-7
TITLE: Methods for Integration of Heterogeneous Real-Time Services into High-Performance Networks
AUTHORS: Magnus Jonsson and Bertil Svensson

This proposal seeks to develop methods to use an existing special control-fibre in a fiber-optic ring interconnect for a multiprocessor to provide soft/hard real-time and quality of service guarantees to applications.

The goal is fine, and such research is interesting to perform. However, the current proposal has some weaknesses. First, and most important, no ideas are stated for how the control-fibre will be used to provide the higher-level or more diverse QoS features the proposal seeks to provide. That the control fibre can be used for such purposes is presumably the purpose of the control fibre in the first place, which is previous work. Nor are any concrete instances provided of the needs of applications that might be satisfied in this way. Thus, there is no reason provided for a reviewer to feel that the investigators will have a high likelihood of success. Second, the case for optical networks as the networks of choice for *multiprocessors* with real-time constraints is not made well. Yes, they have additional bandwidth, but they have not yet proved ready for multiprocessors in general due to the latency/overhead of the conversion between optics and electronics. This is okay, since the research is likely to be valuable anyway, but the investigators should have addressed this. Third, providing real-time guarantees in the interconnect fabric is not nearly enough to provide end-to-end real-time guarantees to an application. This is especially true in multiprocessors where the dominant cost of communication, as well as the dominant contention for resources that can make timing unpredictable, is not in the network fabric but at the end-point nodes of the communication. The authors should have paid some attention to these issues, especially the first, even in a short proposal.

The specific area of the proposal seems relatively untrodden and good methods may come of the research, but the case is not well made.