Christopher Small

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Today’s extensible operating systems allow applications to modify kernel behavior by providing mechanisms for application code to run in the kernel address space. The advantage of this approach is that it provides improved application flexibility and performance; the disadvantage is that buggy or malicious code can jeopardize the integrity of the kernel. It(More)
We investigated how operating system design should be adapted for multithreaded chip multiprocessors (CMT) – a new generation of processors that exploit thread-level parallelism to mask the memory latency in modern workloads. We determined that the L2 cache is a critical shared resource on CMT and that an insufficient amount of L2 cache can undermine the(More)
Pebble is a new operating system designed with the goals of flexibility, safety, and performance. Its architecture combines a set of features heretofore not found in a single system, including (a) a minimal privileged mode nucleus, responsible for switching between protection domains, (b) implementation of all system services by replaceable user-level(More)
The attack on the World Trade Center (WTC) created an acute environmental disaster of enormous magnitude. This study characterizes the environmental exposures resulting from destruction of the WTC and assesses their effects on health. Methods include ambient air sampling; analyses of outdoor and indoor settled dust; high-altitude imaging and modeling of the(More)
DARPA’s Disruption-Tolerant Networking (DTN) program is developing technologies that enable access to information when stable end-to-end paths do not exist and network infrastructure access cannot be assured. DTN technology makes use of persistence within network nodes, along with the opportunistic use of mobility, to overcome disruptions to connectivity.(More)
In 1981, Stonebraker wrote: Operating system services in many existing systems are either too slow or inappropriate. Current DBMSs usually provide their own and make little or no use of those o ered by the operating system. [STON81] The standard operating system model has changed little since that time, and we believe that, at its core, it is the wrong(More)
OBJECTIVE To survey tube wells and households in Araihazar upazila, Bangladesh, to set the stage for a long-term epidemiological study of the consequences of chronic arsenic exposure. METHODS Water samples and household data were collected over a period of 4 months in 2000 from 4997 contiguous tube wells serving a population of 55000, the position of each(More)
Previous studies of DMSP-OLS stable night lights have shown encouraging agreement between temporally stable lighted areas and various definitions of urban extent. However, these studies have also highlighted an inconsistent relationship between the actual lighted area and the boundaries of the urban areas considered. Applying detection frequency thresholds(More)