>> This is actually along similar lines of thought that I had when I was
>> thinking of how to get rid of the builtin VM scheduling behavior. The main
>> thought that I had was that the VM may have a "special" process - the
>> scheduler process (duh!) which it runs when it doesn't know what else to
>> do.
>> The VM would then not directly schedule processes after semaphore signals
>> but rather put them onto a "ready" queue that can be read by the scheduler
>> process and switch to the scheduler process. The scheduler process decides
>> what to run next and resumes the process via a primitive. Whenever an
>> external signal comes in, the VM automatically activates the scheduler
>> process and the scheduler process then decides whether to resume the
>> previously running process or to switch to a different process.
>>
>> In a way this folds the timer process into the scheduler (which makes good
>> sense from my perspective because much of the work in the timer is stuff
>> that could be more effectively take place in the scheduler). The
>> implementation should be relatively straightforward - just add a scheduler
>> process and a ready list to the special objects, and wherever the VM would
>> normally process switch you just switch to the scheduler. Voila, there is
>> your user-manipulable scheduler ;-) And obviously, anything that is run
>> out
>> of the scheduler process is by definition non-interruptable because there
>> is
>> simply nothing to switch to!
>
>
> How would you generalise this to a natively multi-threaded VM? Obviously
> one simple way is to stop the other processors at a suspension point before
> letting the scheduler process proceed, but is there anything cleverer that
> doesn't halt all processors until the singleton scheduler has made its mind
> up?
Every OS thread would have it's own scheduler process. Each scheduler