From: dic5340@hertz.njit.edu (David Charlap)
Newsgroups: comp.os.os2.misc
Subject: Re: Benefits of OS/2?
Date: 13 Apr 92 18:19:41 GMT
Distribution: na
Organization: New Jersey Institute of Technology, Newark, N.J.

In article <1992Apr13.130028.7353@pasteur.Berkeley.EDU> timbol@cory.Berkeley.EDU (Mike Timbol) writes:

>I don't see how this can possibly work (unless you have two 
>identical printers and a really strange driver for this).  
>suppose that (for apps that do this) you could simultaneously 
>build the bitmaps that are sent to the printer, then send them 
>one at a time.  But then you'd have to keep the second bitmap
>in memory while the first was printing.

Yes.  they'd both be in memory (or swapped to disk), but the processor
wouldn't be handling it at that time.  Most programs are bound by I/O
operations.  While the CPU is waiting for I/O on one print thread, it
can be processing another one.

>>Meanwhile, while you have control of the cursor, you may
>>want to open 4 files in a word processor to compare them.  Issue 4
>>open commands within 10 seconds and your word processor will call 4
>>"open" modules that each begin to load the data files.  So, there
>would be 8 programs running simulataneously -- 4 "open file" programs
>>and 4 "print file" programs. 
>
>I don't think this is an advantage at all.  If the four files were 
>all on the same hard disk this would be far worse because of the 
>added seek time jumping back and forth between the files you 
>wanted to open.  (Now, if you had a properly configured RAID 
>setup...)

Most file systems are cached.  You won't notice much degrading.  All
four won't be loaded in the same time it took to load one.  But
processes and threads not associated with the loading and printing can
go on in the spare CPU cycles.  OS/2 will gurantee that there are
enough cycles so that the system doesn't appear to "hang" during these
operations, the way Windows does.

>Overall, I agree that multitasking/multithreading is a good 
>thing, but not in every case.  Multitasking two or more disk
>access (to the same disk) would (I think) degrade performance over 
>doing this sequentially.

Not necessarily.  Even without caching, the delays you speak of are
for the OS waiting for the drive to seek across the disk.  This is
only significant if the only thing you're doing is disk access.
Non-disk programs can do other things while the heads are seeking, so
your overall system performance isn't degraded much (if at all).

>Also, running a spelling check on one
>document while working on another (another popular example)
>doesn't seem to be of much use (at least for me; I usually 
>make enough spelling mistakes to prevent this from being a 
>background task :).

Maybe not on other documents, but picture a spelling checker that
alerts you to spelling errors as you type them.  This exists in some
word processors, but they do it without multithreading, so there's a
delay after each word typed to check it.  This way, an independant
thread can do the checking while you type away.

>A single multithreaded application only has a performance increase
>during periods when the CPU is waiting for something to happen.
>An OS/2 word processor would be better than a Windows word processor
>only because of 32-bit code or while waiting for a file to open or
>save.  Something that takes actual CPU time under Windows will
>still take CPU time under OS/2..

You don't realize how much CPU is wasted during word processing.  The
fraction of a second delay between keystrokes while typing is a long
time for a CPU to go and do other things.

Yes, something that takes actual CPU time will still take it under
OS/2, but I dobt anything a typical user does (besides compiling and
data compression) actually occupies much CPU time.  As an example, I
used a VAX/VMS system for a semester at NJIT.  At the end other
semester, the total CPU time used by me (which involved reading news,
compiling, debugging, and generally being on line 3 hours a day) came
to less than five minutes.


-- 
David Charlap                   Q:"Where do these stairs go?"
dic5340@hertz.njit.edu          A:"They go up"
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