Week 9 Bench: Sharing a tenant

Working out, from the outside, whether two processes are colocated on the same physical machine

19 April 2027

Before the Bench#

Read the placement sections of Ristenpart et al., 2009 — the internal-IP map and the round-trip-time check, not the extraction results — before arriving. This Bench works from supplied data rather than a live cloud account.

In the Bench#

Using supplied round-trip-time and shared-cache-contention data from pairs of cloud instances, decide which pairs were probably colocated on the same physical host and which were not. The exercise sits one layer up from week 6’s cache measurement: there the question was which addresses a neighbour touched, here it is whether a neighbour exists on the same hardware at all, which is the precondition every cross-tenant channel in this course’s second half depends on.

Afterwards#

Note which signal you trusted most. Providers have spent a decade making exactly that signal noisier — worth knowing which one you would reach for first, and which one is likely already defended against.