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Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!rutgers!bpa!cbmvax!vu-vlsi!dsinc!lgnp1!prapc2!paulr
From: paulr@prapc2.pra.COM (Paul Raulerson)
Newsgroups: unix-pc.general,comp.sys.att
Subject: Re: Question about windows and processor time (3b1)
Message-ID: <282@prapc2.pra.COM>
Date: 22 Feb 89 13:36:41 GMT
References: <356@flatline.UUCP>
Reply-To: paulr@prapc2.pra.COM(Paul Raulerson)
Organization: Paul Raulerson & Associates, Norristown PA.
Lines: 44

In article <356@flatline.UUCP> erict@flatline.UUCP (j eric townsend) writes:
>
>Set up 4 or 5 windows to page through.
>Using the new wmgr from THE STORE -- the one that lets you hot key through
>the windows -- page through the windows at about one per second.
>
>Does your hard drive *pause* while you go from one window to another?
>Mine does.
>
>I thought Unix was multitasking, etc etc.  I didn't think it would
>have to stop HDU access just to change windows.  Am I missing something
>vital>


Unix is *not* multi-tasking, it merely appears to be so.
Unix  really does a little magic trick (at least on the 3B1
as well as most other Unix machines) called "time slice" or
"Processor sharing".  It is probable that nothing truely
"paused",  just so much processor attention was paid to your
context switch that nothing did enough work to need to
access the disk again for a second or so.  This happens on
every Unix machine I have ever encountered.  Second, if your
machine does not have plenty of memory, something may
actually have "swapped" out of processor space when you
changed windows.   Thirdly, jobs in the background are
usually ran at lower priority than jobs in the foreground,
so Unix stole processor cycles from the compiles you had
running to execute your window shift.   It could have been
any one of these three reasons, or any combination of them.

Now as to the wmgr fro the STORE... is it pd and where could
I get a copy?  This windowing interface is driving me batty;
I am too used to Sun interfaces now.  I would love to have
about 4 virtual consoles though.  Anyone cooked up a
replacement for the thingamboob yet that can handle that?

Paul


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