Showing papers by "Rodrigo Fonseca published in 2010"

Experiences with tracing causality in networked services

Abstract: Unlike device-centric monitoring, task-centric tracing enables an operator to causally trace the complete execution of a networked system across the boundaries of applications, protocols, and administrative domains. In this paper, we argue that causal, end-to-end tracing should be an integral part of network services. Moreover, it is not fundamentally difficult to achieve, given a primitive that propagates task metadata alongside logical execution and communication paths. X-Trace is a framework that relies on such propagation to provide comprehensive causal tracing. We report on our experience integrating X-Trace into several production networked services--including 802.1X authentication, Web content distribution, and DNS-based replica selection--to illustrate benefits of causal tracing, and to discuss the instrumentation of different protocols and component architectures. We highlight the challenges we encountered and techniques we developed to better integrate causal tracing into network services.

System for providing scalable in-memory caching for a distributed database

Abstract: A system is described for providing scalable in-memory caching for a distributed database. The system may include a cache, an interface, a non-volatile memory and a processor. The cache may store a cached copy of data items stored in the non-volatile memory. The interface may communicate with devices and a replication server. The non-volatile memory may store the data items. The processor may receive an update to a data item from a device to be applied to the non-volatile memory. The processor may apply the update to the cache. The processor may generate an acknowledgement indicating that the update was applied to the non-volatile memory and may communicate the acknowledgment to the device. The processor may then communicate the update to a replication server. The processor may apply the update to the non-volatile memory upon receiving an indication that the update was stored by the replication server.

Inferring router statistics with IP timestamps

Abstract: This paper describes our initial experiences with using the IP timestamp option to infer router statistics such as traffic shape and CPU load. By deducing this information through the use of an IP option, we can gather these statistics without administrative access to the router under study. This creates the potential for researchers to gather basic statistics from routers in wide-area networks which support this option.

Network-wide energy profiling of CTP

Abstract: We present our experiences evaluating the power-performance tradeoffs of a sensornet network protocol on a power-aware testbed. We characterize the power draw of the entire network while running the Collection Tree Protocol (CTP), as a function of low-power-listening interval. We find that message transmission counts are poor predictors for energy consumption on the CC2420 radio, that CTP routinely creates energy hotspots in the routing tree, and that conclusions based on protocol evaluation performed without low-power listening enabled provide little insight about the same protocol performance using low-power listening.