Real-time systems often use SPM instead of cache, because SPM allows a program¡¦s run time to be more predictable. Real-time system need predictable runtimes, because they must schedule programs to finish within specific deadlines. A deadline should be larger than its program¡¦s worst-case execution time (WCET). Our laboratory is conducting ongoing research into scratchpad memory allocation (SPM) for reducing the WCET of a program. Compared to our previous work, this current thesis improves our memory model, our allocation algorithms, our real-time support, and our measurement benchmarks and platform. Our key accomplishments in this paper are to: 1) add, for the first time in the literature, true WCETmeas analysis to an SPM allocator, 2) to modestly improve the performance of our previous allocator, and 3) to greatly increase the applicability over that allocator, by extending the method to support recursive programs.

Scratchpad memory (SPM) is popular for real-time embedded systems. Whereas caches use a memory management unit (MMU) to control which data accesses go to the fast, on-chip SRAM, SPM directly maps certain addresses to the SRAM. One advantage of SPM is that it avoids the cache¡¦s costly MMU. Another advantage is that the SPM is 100% statically predictable, whereas the variables stored in the cache depend upon the dynamic execution history. This predictability is beneficial for real-time systems which must schedule tasks to finish by fixed deadlines. To set these deadlines, system designers must determine the worst-case execution times (WCETs) of the applications. The predictability of SPM makes these WCETs easier to measure. This thesis presents a new method for allocating stack and global data to the SPM. It is the first method to make use of the special properties of non-escaping variables so as to increase the effective size of the SPM. Our insight is that many local variables of caller functions can be temporarily swapped out of the SPM while the callee function executes. Ours is also the first method to support profiled WCET measurements in the allocation strategy. Most previous SPM methods optimize only for the average-case execution time (ACET), despite the fact that SPMs are often used in real-time environments where the WCET is also important. This new memory allocation strategy is also the first to be WCET/ACET tunable, a feature that is particular useful for soft real-time systems. Only one previous work considers a WCET-targeted SPM allocator. That work, however, only applies to static WCET analysis tools. Such tools are difficult to program and are not widely used. Also, they only have application to the most safety-critical of real-time systems. In contrast, our approach is the first to employ measurement-based WCET analysis (such as is most commonly used in industry) for SPM allocation.

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Women constitute the largest proportion of the rural adult South African population. The rural areas host women with the lowest levels of education and skills training in the country. The lack of basic education and skills has resulted in many of them being marginalised, rejected and discriminated against, unemployed and living in poverty. These social problems have serious negative effects on them and their families, which is why the educational provision of Adult and Community Education and Training in South Africa is a significant tool for their socio-economic advancement. This educational provision is aimed at empowering adults in general, and rural women in particular, with the necessary livelihood skills to lead productive lives and consequently the study sought to investigate the socio-economic lives of rural women through skills training for poverty reduction in the Mthatha area of South Africa. A qualitative research approach and an exploratory design were employed for the study. A sample of 35 participants, comprising 20 female learners, 4 educators, and 7 former learners were in addition to 4 learners selected for a focus group discussion. Other instruments with which data were collected constituted in-depth individual interviews and documentary analysis. The theories underpinning the study are Maslow‘s theory of motivation, empowerment theory and critical pedagogy. Among others, the findings revealed the absence of adequate resources with which to empower rural women and consequently the study recommends that Adult and Community Education and Training providers include programmes that can up-skill rural women based at community learning centres in an effort to enhance their economic development. Community learning centres must be fully resourced in terms of facilities and appropriate learning tools to render Adult and Community Education and Training a beneficial educational intervention for these rurally based women. / Educational Studies / Ph. D. (Socio-Education)