SimSight: A Virtual Machine Based Dynamic Call Graph Generator

One problem with using component-based software development approach is that once software modules are reused over generations of products, they form legacy structures that can be challenging to understand, making validating these systems difficult. Therefore, tools and methodologies that enable engineers to see interactions of these software modules will enhance their ability to make these software systems more dependable. To address this need, we propose SimSight, a framework to capture dynamic call graphs in Simics, a widely adopted commercial full-system simulator. Simics is a software system that simulates complete computer systems. Thus, it performs nearly identical tasks to a real system but at a much lower speed while providing greater execution observability. We have implemented SimSight to generate dynamic call graphs of statically and dynamically linked functions in x86/Linux environment. A case study illustrates how we can use SimSight to identify sources of software errors. We then evaluate its performance using 12 integer programs from SPEC CPU2006 benchmark suite.

Xenia Effects on Quality of Maize Female Inbred in Production of Hybrid Seeds

In Maize (Zea maize L.), cost of hybrid seed production is directly related to the yield and quality of seed obtained per hectare of female parent. It is also important to consider the effects that a male parent can exert on the development of hybrid seed in the female parent. This effect is known as xenia. The objectives of this study were to evaluate xenia effects on 1) yield as 80K units, 2) germination of the hybrid seed and 3) susceptibility of the hybrid seed to mechanical damage. One female inbred and four male inbred lines were selected from a parent list of hybrids. The experiment was designed to allow individual cross pollination between each male inbred and the female inbred line. For use as a control, the female inbred was allowed to self pollinate. Experiments were conducted in Illinois and Iowa during 2008 and 2009 and in Nebraska during 2009. A significant inbred effect was detected on yield as 80k (α=0.001). The selfed female and pollination with male inbred B resulted in lower yields of hybrid seed. For germination, a significant inbred effect was detected (α=0.001), but was due to lower germination percentage of seed produced on the selfed female. All hybrid combinations resulted in higher germination percentages with no significant differences among hybrids. The inbred x mechanical damage interaction was significant (P=0.04) for effects on cold saturated soil germination tests. Use of inbred B resulted in a two-percentage-point reduction in cold germination when treated with the impact simulator. In a maize seed company, the production research group provides yield estimates for production of new hybrid combinations. Results from this study indicate that using only the female inbred yield may provide inaccurate estimates. Therefore to improve yield estimation, experiments should be designed to include male inbreds. Male inbreds can also impart a negative effect to the hybrid seed on tolerance to mechanical damage, thus lowering quality and increasing seed discard. When testing for hybrid seed germination, there is no need to consider distinct hybrid combinations. Female inbreds can be grown in open-pollinated fields to avoid loss of vigor observed with selfing. Advisor: George Graef