A measurement-based simulation study of processor co-allocation in multicluster systems

In systems consisting of multiple clusters of processors interconnected by relatively slow network connections such as our Distributed ASCI Supercomputer (DAS), applications may benefit from the availability of processors in multiple clusters. However, the performance of single-application multicluster execution may be degraded due to the slow wide-area links. In addition, scheduling policies for such systems have to deal with more restrictions than schedulers for single clusters in that every component of a job has to fit in separate clusters. In this paper we present a measurement study of the total runtime of two applications, and of the communication time of one of them, both on single clusters and on multicluster systems. In addition, we perform simulations of several multicluster scheduling policies based on our measurement results. Our results show that in many cases, restricted forms of co-allocation in multiclusters have better performance than not allowing co-allocation at all

A dynamic co-allocation service in multicluster systems

In multicluster systems, and more generally in grids, jobs may require co-allocation, i.e., the simultaneous allocation of resources such as processors in multiple clusters to improve their performance. In previous work, we have studied processor co-allocation through simulations. Here, we extend this work with the design and implementation of a dynamic processor co-allocation service in multicluster systems. While an implementation of basic co-allocation mechanisms has existed for some years in the form of the DUROC component of the Globus Toolkit, DUROC does not provide resource-brokering functionality or fault tolerance in the face of job submission or completion failures. Our design adds these two elements in the form of a software layer on top of DUROC. We have performed experiments that show that our co-allocation service works reliably.

Circadian disruption impairs glucose homeostasis in male but not in female mice and is dependent on gonadal sex hormones

Circadian disruption (CD) is the consequence of a mismatch between endogenous circadian rhythms and behavior, and frequently occurs in shift workers. CD has often been linked to impairment of glucose and lipid homeostasis. It is, however, unknown if these effects are sex dependent. Here, we subjected male and female C57BL/6J mice to 6-h light phase advancements every 3 days to induce CD and assessed glucose and lipid homeostasis. Within this model, we studied the involvement of gonadal sex hormones by injecting mice with gonadotropin-releasing hormone-antagonist degarelix. We demonstrate that CD has sex-specific effects on glucose homeostasis, as CD elevated fasting insulin levels in male mice while increasing fasting glucose levels in female mice, which appeared to be independent of behavior, food intake, and energy expenditure. Absence of gonadal sex hormones lowered plasma insulin levels in male mice subjected to CD while it delayed glucose clearance in female mice subjected to CD. CD elevated plasma triglyceride (TG) levels and delayed plasma clearance of TG-rich lipoproteins in both sexes, coinciding with reduced TG-derived FA uptake by adipose tissues. Absence of gonadal sex hormones did not notably alter the effects of CD on lipid metabolism. We conclude that CD causes sex-dependent effects on glucose metabolism, as aggravated by male gonadal sex hormones and partly rescued by female gonadal sex hormones. Future studies on CD should consider the inclusion of both sexes, which may eventually contribute to personalized advice for shift workers

Circadian disruption impairs glucose homeostasis in male but not in female mice and is dependent on gonadal sex hormones

Circadian disruption (CD) is the consequence of a mismatch between endogenous circadian rhythms and behavior, and frequently occurs in shift workers. CD has often been linked to impairment of glucose and lipid homeostasis. It is, however, unknown if these effects are sex dependent. Here, we subjected male and female C57BL/6J mice to 6-h light phase advancements every 3 days to induce CD and assessed glucose and lipid homeostasis. Within this model, we studied the involvement of gonadal sex hormones by injecting mice with gonadotropin-releasing hormone-antagonist degarelix. We demonstrate that CD has sex-specific effects on glucose homeostasis, as CD elevated fasting insulin levels in male mice while increasing fasting glucose levels in female mice, which appeared to be independent of behavior, food intake, and energy expenditure. Absence of gonadal sex hormones lowered plasma insulin levels in male mice subjected to CD while it delayed glucose clearance in female mice subjected to CD. CD elevated plasma triglyceride (TG) levels and delayed plasma clearance of TG-rich lipoproteins in both sexes, coinciding with reduced TG-derived FA uptake by adipose tissues. Absence of gonadal sex hormones did not notably alter the effects of CD on lipid metabolism. We conclude that CD causes sex-dependent effects on glucose metabolism, as aggravated by male gonadal sex hormones and partly rescued by female gonadal sex hormones. Future studies on CD should consider the inclusion of both sexes, which may eventually contribute to personalized advice for shift workers.Metabolic health: pathophysiological trajectories and therap

Parallel job scheduling - a status report

The popularity of research on the scheduling of parallel jobs demands a periodic review of the status of the field. Indeed, several surveys have been written on this topic in the context of parallel supercomputers [17, 20]. The purpose of the present paper is to update that material, and to extend it to include wor