SPEED UPS

As indicated in the previous chapter, the system overheads were quite high (e.g., on the order of 20 milliseconds per data block transferred from the disk). In this chapter we will consider the possible effects of some improvements we had intended to implement. In the next chapter we will consider possible hardware improvements. We had two intended improvements, both to the ECS system:

• Direct ECS Access
  • A subprocess could select a single data block in a single ECS file and be given direct hardware access to its contents.
• Fast Actions
  • A small number of ECS actions would be recoded in an ad hoc, but hopefully more efficient, manner.

It is probably that these two changes, together with a minor change in the disk system, would have reduced the per block overhead for disk transfers to the order of 10 milliseconds for multiblock transfers.