3.1 Space-Time Resource Graph
The Space-Time Resource Graph (STRG) is central to
our approach. It contains the current distribution of system resources to Cells and is updated by the Policy Service to reflect the changing needs of the system. As it
changes, copies of the STRG are passed to the Tessellation kernel for validation and implementation.
Each leaf of the STRG represents an admitted Cell and
contains the current resource assignments for that Cell,
including guaranteed fractions of caches and memory
bandwidth, the Cell activation policy (see Section 3.3),
and a list of QoS guarantees for system services. It also
indicates the Cell’s desire to receive excess resources.
Interior nodes of the STRG group Cells into resource
groups, providing a mechanism for assigning resources
to related Cells. For instance, resource groups provide an
obvious mechanism for distributing resources to multiple
Cells that are part of a single application or service domain
2
. As another example, Tessellation’s pre-allocation
mechanism allows resources to be reserved for future use
by a particular Cell while exported to other Cells in a resource group as temporary (revocable) excess resources.