A Pruning-Based Disk Scheduling Algorithm for Heterogeneous I/O Workloads

Figure 2

An example for pruning. There are three requests 𝑅₁, 𝑅₂, and 𝑅₃ in the queue. Schedules 𝑆₁ and 𝑆₆ can be pruned because 𝑆₁ misses the deadline 200 ms of 𝑅₁, and 𝑆₆ incurs too long seek times.

(a) Requests 𝑅_𝑖(𝑑_𝑖,𝑡_𝑖) in the queue: 𝑑_𝑖 is the deadline and 𝑡_𝑖 is the track number

(b) All possible schedules: node (𝑅_𝑖, 𝑅_𝑗, 𝑅_𝑘) denotes the scheduling order of 𝑅𝑖→𝑅_𝑗→𝑅_𝑘