low priority processes

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3 total messages Started by Ian Gorton Wed, 17 May 1989 13:29

#2687

Author: Ian Gorton
Date: Wed, 17 May 1989 13:29

22 lines
1120 bytes

Just a quick question.....


Consider a scenario where there are many processes instantiated on a 
transputer, but only one low priority process is able to execute, and this
situation lasts for quite a long time (perhaps a second or 2).

I assume this process, the only executable process, will be treated as all
low priority process are normally treated, and be timesliced at regular
intervals. 

Though as it is the only process able to run, I also assume it will be
immediately become active again.

The question is...(if my assumptions are correct?!), what is the time
interval between the process being de-activated and it becoming active 
again. Not very much, I (again) assume. 

Anyone know  the answer (Inmos yet again assume)    

Yours assumptiously..... Ian

Re: low priority processes

#2690

Author: Peter Dodd
Date: Sat, 20 May 1989 04:49

23 lines
1112 bytes


Ian,
  Given a low priority process executing alone :

> The question is...(if my assumptions are correct?!), what is the time
> interval between the process being de-activated and it becoming active 
> again. Not very much, I (again) assume. 

  Im not sure, but it will be one of two cases :

1) The processor deschedules the process then reschedules the process
   who's workspace is pointed to by the FPtr1 register, which will take 
   less than 1us. ( Normal context switch time )

2) The processor will recognise that the FPtr1 and current Workspace
   registers are identical, and continue execution without descheduling.
   Even less time than context switching. 

Peter.

----------------
peter@wacsvax.oz

Re: low priority processes

#2691

Author: Peter Dodd
Date: Sat, 20 May 1989 09:35

17 lines
982 bytes

Sorry for the repost...

>  Given a low priority process executing alone :
>
>> The question is...(if my assumptions are correct?!), what is the time
>> interval between the process being de-activated and it becoming active 
>> again. Not very much, I (again) assume. 
>
>  Im not sure, but it will be one of two cases :

Of course it will be neither, since both FPtr1, and BPtr1 will be NULL.
As they point to workspaces that are active awaiting execution, excluding
the currently executing process. Hence descheduling cannot occur.

Peter.
----------------
peter@wacsvax.oz

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