[comp.sys.amiga] priorities

pds@quintus.uucp (Peter Schachte) (06/21/88)

In article <1814@van-bc.UUCP> lphillips@lpami.van-bc.UUCP (Larry Phillips) writes:
>In <3043@louie.udel.EDU>, CRONEJP%UREGINA1.BITNET@cornellc.ccs.cornell.edu (Jonathan Crone) writes:
> >ACtually the problem with RSL Clock was that the twit who wrote it
> >had the program set itself up with a prioiryt of 20.
>Nice attitude Jonathan. Someone writes you a nice clock and you call him a
>twit for making a mistake.

Maybe this is a naive question, but why is it a mistake to make a clock
program run at priority 20?  If you really want the clock kept up-to-date,
and it runs pretty fast, why not run at priority 20?  Isn't that what
priorities are for?  Who misses a couple of milliseconds every second?
-Peter Schachte
pds@quintus.uucp
..!sun!quintus!pds

thad@cup.portal.com (06/22/88)

The filesystem runs at priority 10, the trackdisk.device runs at priority 5.

If you NEED to know the wall-clock time every second, visit your nearest
Far East Import Car Dealer, take a test drive, and get a free digital watch.

Or for $1 buy one of those circular stick-on digital clocks and affix it to
one corner of your monitor's case.

Though the Amiga is a fine multi-tasking system, overburdening it with
excessive tasks will cause it to reach a performance "knee" at which it
appears to stop.

rgj@killer.UUCP (Randy Jouett) (06/26/88)

In article <128@quintus.UUCP> pds@quintus.UUCP (Peter Schachte) writes:
>In article <1814@van-bc.UUCP> lphillips@lpami.van-bc.UUCP (Larry Phillips) writes:
>>In <3043@louie.udel.EDU>, CRONEJP%UREGINA1.BITNET@cornellc.ccs.cornell.edu (Jonathan Crone) writes:
>> >ACtually the problem with RSL Clock was that the twit who wrote it
>> >had the program set itself up with a prioiryt of 20.
>>Nice attitude Jonathan. Someone writes you a nice clock and you call him a
>>twit for making a mistake.
>
>Maybe this is a naive question, but why is it a mistake to make a clock
>program run at priority 20?  If you really want the clock kept up-to-date,
>and it runs pretty fast, why not run at priority 20?  Isn't that what
>priorities are for?  Who misses a couple of milliseconds every second?
>-Peter Schachte
>pds@quintus.uucp
>..!sun!quintus!pds

	This is one of the reasons why VoiceClock does not stay resident.
Using vclock along with a macro/hot-key (I use ALT-ESC with dmouse -- great
prog, Matt!) program makes sure that the 68K gets every cycle it deserves.
Other major advantages vclock has over other clock progs are: size (1392 bytes);
it can be used by the blind, and, as stated above, it does not require a high
process priority for accuracy.

NOTE: "It is now" is a bug -- posted wrong version :(. It should been "It is"
followed by the time.

-- Randy

...!killer!rgj   
 

vkr@osupyr.mast.ohio-state.edu (Vidhyanath K. Rao) (06/26/88)

In article <4601@killer.UUCP>, rgj@killer.UUCP (Randy Jouett) writes:

> In article <128@quintus.UUCP> pds@quintus.UUCP (Peter Schachte) writes:
>> Maybe this is a naive question, but why is it a mistake to make a clock
>> program run at priority 20?[...]  Who misses a couple of milliseconds
>> every second?

> [...] it does not require a high process priority for accuracy.
The question is how often the clock program wakes up. Any program that
must do something at regular intervals is supposed to the timer.device
alarms. If that is the case the arguments are correct. 

The norm for such programs on 'lesser' machines is to put something in
the interrupt server for the interrupt that occurs every 1/60th of a sec.
Whether a clock programmer is a twit depends on this. Actually these
type of programs on the C64 were written by twits: They screw up the
vectors and the server chains. 

I haven't seen the source to any of these clock programs. So the comments
above are not directed against anybody in particular.

Finally, if the code executed takes only 2-3ms, the priority is irrelevent.
How do you set clock to 2ms accuracy? Do you have a Cessium clock or like?

pds@quintus.uucp (Peter Schachte) (06/28/88)

In article <635@osupyr.mast.ohio-state.edu> vkr@osupyr.mast.ohio-state.edu (Vidhyanath K. Rao) writes:
>Finally, if the code executed takes only 2-3ms, the priority is irrelevent.
>How do you set clock to 2ms accuracy? Do you have a Cessium clock or like?

No, what I meant is:  if a clock only takes a few milliseconds to update
the display each time it does so, who cares if it runs every second, at
priority 20?  The question I'm really asking is:  can anything go wrong
on the Amiga if I have a process running at such a high priority?
Suppose it's a really badly written clock, and takes half a second to
update the clock every second, running at priority 20.  Can it cause the
system to crash, or cause read/write errors on a DMA hard disk, or
anything else serious?  Or is the worst that can happen that I waste
some time, and slow down the machine?
-Peter Schachte
pds@quintus.uucp
..!sun!quintus!pds