Optimizing Capacitance and Switching Activity to Reduce Dynamic Power - Computer Architecture Techniques for Power-Efficiency - page 75

4.6 IDLE-CAPACITY SWITCHING ACTIVITY:
INSTRUCTION QUEUE
Following Albonesi's work on complexity adaptive structures, a number of researchers proposed
to dynamically adapt the instruction queue to the needs of programs, but now having power
consumption—rather than performance— in their sights. Table 4.5 gives an overview of the
proposals we present here.

4.6.1 Physical Resizing
Buyuktosunoglu and Albonesi teamed up with Schuster, Brooks, Bose, and Cook from IBM and
published one of the first papers addressing over-provisioned activity in the instruction queue.

TABLE 4.5: Techniques to Adapt the Issue Queue to Program Behavior

Technique Partitioning Resizing Feedback Control

Buyuktosunoglu
et al. [ 42 ]

Physical
partitioning into
segments
Partitioning of the
IQ is achieved
with buffered
wires

Physical resizing :
enabling or
disabling
consecutive IQ
segments

Readiness Feedback:
Readiness measured as
the number of “active”
segments (having the
majority of their entries
ready-to-issue )
IPC feedback for limiting
performance
degradation

Ponomarev,
Kucuk, and
Ghose [ 182 ]

Physical into
segments

Physical resizing:
enabling or
disabling IQ
segments

Occupancy Feedback:
Instruction Queue
Occupancy measured as
the fraction of valid
entries

Folegnani and
Gonzalez [ 80 ]

Logical into
segments

Logical resizing
without
partitioning: part
of the empty
space is excluded
from allocation to
new entries

ILP Contribution
Feedback: usefulness of
(logical) segments in
issuing instructions