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Re: The Scheduler

This page is part of the web mail archives of SRFI 18 from before July 7th, 2015. The new archives for SRFI 18 contain all messages, not just those from before July 7th, 2015.

> Marc: What about weakening the definition of priority to allow other
> comparable values such as real numbers or (more specifically) time
> objects? With this, I am sure a RT-SRFI could be written without
> having to undo parts of SRFI-18.

I could see using real numbers for priorities, which would allow
deadlines to be expressed (i.e. you set the priority to
(- (time->seconds deadline)) for threads with deadlines, otherwise you
use a positive value for threads without a deadline).

My only worry is that this prevents certain efficient implementations.
For example, you can't represent the set of runnable threads as a
table of lists of threads indexed by priority (a common way to
implement priorities in other thread systems).  Also, with integer
priorities, a system that does not implement priorities can define
(thread-min-priority) and (thread-max-priority) to return the same
integer.  However, if priorities are real, then I see no reason to
keep (thread-min-priority) and (thread-max-priority).

Anybody have a strong opinion about this?