In Defense of Snooping Employers

Scalable Subspace Snooping

Snooping tag bandwidth is one of the resources that limits the number of processors that can participate in a cache-coherent snooping system. In this paper, we evaluate a type of coherence protocol called subspace snooping, which decouples the snoop tag bandwidth from the address bus bandwidth. In subspace snooping, each processor snoops a set of logical channels, which are a subset of the tota...

Bandwidth Adaptive Snooping

This paper advocates that cache coherence protocols use a bandwidth adaptive approach to adjust to varied system configurations (e.g., number of processors) and workload behaviors. We propose Bandwidth Adaptive Snooping Hybrid (BASH), a hybrid protocol that ranges from behaving like snooping (by broadcasting requests) when excess bandwidth is available to behaving like a directory protocol (by ...

Snooping on Space Pictures

Detecting Traffic Snooping in Tor Using Decoys

Anonymous communication networks like Tor partially protect the confidentiality of their users’ traffic by encrypting all intraoverlay communication. However, when the relayed traffic reaches the boundaries of the overlay network towards its actual destination, the original user traffic is inevitably exposed. At this point, unless end-toend encryption is used, sensitive user data can be snooped...

Directories vs. Snooping in Chip-Multiprocessor

Advances in semiconductor integration technology have resulted in ever increasing transistor density. This has led to designs where multiple processors, each with its own caches, memory controller, network interface, as well network router, are integrated in a single chip. Previously understood and deeply explored tradeoffs in conventional multiprocessor systems need to be reevaluated. We chose...