Handbook 3.2.2: Freebsd a multiprocessing system?
cswiger at mac.com
Tue Jan 12 17:55:16 UTC 2010
On Jan 12, 2010, at 12:52 AM, Pieter Verberne wrote:
> Section 3.2.2 of the FreeBSD handbook says:
> "FreeBSD is a multiuser, multiprocessing system. This is the formal
> description that is usually given to a system that can be used by many
> different people, who simultaneously run a lot of programs on a single
> Isn't running programs simultaneously called time-sharing?
No. A time-sharing or batch processing system traditionally used to process entire jobs to completion-- think of Hollerith card based machines or early cooperative multitasking implementations and you'll get the idea. Because FreeBSD has a scheduler interrupt firing at typically HZ=100 or 1000, which will pre-empt any userland task and allow other userland tasks to run without any of them being explicitly coded to yield the CPU, FreeBSD is correctly described as a "preemptive multitasking OS".
> Wikipedia says:
> "Multiprocessing is the use of two or more central processing units
> (CPUs) within a single computer system."
> Okay, FreeBSD might use more than one CPU at the time, but the handbook
> is still incorrect I think.
FreeBSD does support multiprocessing per that definition also.
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