7 research outputs found
Data Layout Optimization and Code Transformation for Paged Memory Systems
Supercomputers need not only to have fast functional units, but also to have rapid access to massive quantities of data. Virtual memory paging and physically distributed memory systems both attempt to provide this large data space, but performance of a computer system using either memory organization is highly dependent on the page reference pattern and the number of pages available locally. Despite this, surprisingly little work has been done toward using the compiler to optimize memory system performance. In this paper, we introduce compiler techniques which use a combination of data layout and code transformation to improve paging performance for compiled programs. These same techniques can also be applied manually to improve performance using existing compilers
A study of sampling, granularity and localities in program restructuring
Program restructuring is a method to reduce the cost of program execution by improving the locality of the program\u27s reference behavior. Three aspects of program restructuring (sampling, granularity, localities) are studied in this research. The study of first aspect, sampling, shows that the high cost of a posteriori restructuring can be reduced considerably by a program restructuring method based on sampled reference strings rather than on complete reference string;The second aspect is granularity. Based on the studies of two different block sizes (the basic-block and the procedure block), it is found that the performance of restructuring using smaller blocks is not necessarily better;Finally, a new strategy-independent restructuring method, using both the critical and locality principles, is found to be more effective than any other existing restructuring methods;Results of measurements of paging performance obtained in the experiments are discussed. Both fixed-space and variable-space paging policies are considered
An accurate prefetching policy for object oriented systems
PhD ThesisIn the latest high-performance computers, there is a growing requirement for
accurate prefetching(AP) methodologies for advanced object management schemes
in virtual memory and migration systems. The major issue for achieving this goal is that
of finding a simple way of accurately predicting the objects that will be referenced in
the near future and to group them so as to allow them to be fetched same time. The
basic notion of AP involves building a relationship for logically grouping related
objects and prefetching them, rather than using their physical grouping and it relies on
demand fetching such as is done in existing restructuring or grouping schemes. By this,
AP tries to overcome some of the shortcomings posed by physical grouping methods.
Prefetching also makes use of the properties of object oriented languages to
build inter and intra object relationships as a means of logical grouping. This thesis
describes how this relationship can be established at compile time and how it can be
used for accurate object prefetching in virtual memory systems. In addition, AP
performs control flow and data dependency analysis to reinforce the relationships and
to find the dependencies of a program. The user program is decomposed into
prefetching blocks which contain all the information needed for block prefetching such
as long branches and function calls at major branch points.
The proposed prefetching scheme is implemented by extending a C++
compiler and evaluated on a virtual memory simulator. The results show a significant
reduction both in the number of page fault and memory pollution. In particular, AP
can suppress many page faults that occur during transition phases which are
unmanageable by other ways of fetching. AP can be applied to a local and distributed
virtual memory system so as to reduce the fault rate by fetching groups of objects at the
same time and consequently lessening operating system overheads.British Counci
Locality in logical database systems : a framework for analysis.
Thesis. 1978. M.S.--Massachusetts Institute of Technology. Alfred P. Sloan School of Management.MICROFICHE COPY AVAILABLE IN ARCHIVES AND DEWEY.Bibliography: leaves 106-109.M.S