Re: CPU Scheduling Which statement is true?

From: Bill Vermillion (bv_at_wjv.com)
Date: 10/20/05


Date: Thu, 20 Oct 2005 14:35:01 GMT

In article <1128653773.410247.243570@g49g2000cwa.googlegroups.com>,
 <zeus2@hotmail.com> wrote:
>hi all, i was wondering which two of these statems are true. I am
>having trouble finding information on pinpointing my question to which
>2 statements are correct in terms of Unix.

A true false test? In Unix most answers are "it depends".

>1. BSD UNIX uses a combination of Priority scheduling and Round Robin
>scheduling, which is designed to benefit interactive processes.
>Priorities are recomputed every 2 seconds.

The documentation on this starts with Version 6 of AT&T Unix and
gets slowly changed. Those doc date to the early 1970s.

>2. Processes doing disk I/O or other important tasks have special
>priorities but can be killed by signals when necessary.

I suggest reading a book on the design of Unix. As above - "it
depends" on whether you can kill something or not.

>3. The more CPU time a process accumulates, the lower its priority
>becomes, and vice versa. BSD uses a 0.2-second quantum for the Round
>Robin scheduling.

Ah another "that depends"

...

I suggest a bit of reading and 'true/false' statements regarding
Unix >almost< all fit the 'that depends' category?

Bill

-- 
Bill Vermillion - bv @ wjv . com


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