Arachne Open Issues

PACKING REPLICATED WRITES (Utilizing CPU Time while waiting on replicated writes)

LOAD BALANCING BETWEEN CORES

• Choosing an idle core for a new task
• New task creation when all cores are busy (Slow path for user thread creation)
  • Single Global Queue vs Per-Core Queues needs an experiment.
• Task migration to balance load? (may not be needed if tasks are sufficiently short-lived)

LOGICAL CONCURRENCY VS DESIRED PARALLELISM (CORE COUNT)

• When should we ask the kernel for more cores, and when should we return cores to the kernel?

TIMING GUARANTEES UNDER COOPERATIVE THREADING

• Can we have any kind of timing guarantees without preemption?

PRIORITIES AND STARVATION

BENEFITS / SELLING POINTS / CONTRIBUTIONS

USER API

• How much of knowledge of cores should bubble up to the application?
• What kind of guidance / hints can application offer to Arachne? e.g. priorities.

KERNEL API

CORE NEGOTIATION PROTOCOL

PROPOSED EXPERIMENTS

Mostly Solved Issues

MINIMUM TIME TO SCHEDULE A USER THREAD ONTO ANOTHER CORE

• What is the correct architecture for the fast path, and what is the lowest possible time to schedule to another core?

DEFINITION OF CORE AWARE

• Knowledge of the number of nature of physical cores must move up the stack from the kernel into user-level libraries and possibly into applications