... processes¹

To perform memory management for the multi-process version of Hummingbird, the processes have a shared memory region which is used for malloc().

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... pause²

We call this timing mode THROTTLE. We have implemented two other different timing modes: REAL and FAST. REAL issues the event with the frequency that they were recorded. FAST processes the events with a speed-up heuristic parameterized by $n$; if the time between events is longer than time $n$, then we only wait time $n$ between them.

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... cache³

We controlled the size of the file system buffer cache by locking the Squid's memory using the mlock system call and locking additional memory, so that file system buffer cache could use only the remaining unlocked memory. In this way we also prevented paging of the Squid process.

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