RE: Propeller heads and timing calls
RE: Propeller heads and timing calls
- Subject: RE: Propeller heads and timing calls
- From: email@hidden
- Date: Tue, 16 Jul 2002 05:57:20 EDT
Timing Accuracy:
Time is evoked from the system clock, which runs independent of the
processor(s)... It varies in accuracy from machine to machine, but is
consistant on any given machine over spans of time.
Thus the only issues about gathering time is when you need
it, and how accurate your reference needs to be....
If you want the time and then want to display it, in
theory, another process could grab a timeslice of the
processor between the call to load time and the call for
the display of it, thus ruining it's accuracy (this is
particularly relevant if you are running external processes
that consume a majority of the timeslice, such as video
games, where the delay can be seconds or even minutes
before that process releases the processor for other apps).
On the other hand, from a call to load a time variable
until the fulfillment of the call, as an event, should
incur no significant timing inaccuracy (in seconds, may be
off by a tick or two if measuring in ticks), as the call
should be fulfilled before the processor controller cycles
to another process.
Now, if you talking about measuring run-time of your
scripts, yes, everything (any process or call) that is
going on the machine during your script will effect the
time the script takes to run in general. Disk access in
particular with IDE drives can induce a very noticable
time-delay (SCSI drives don't induce the same overhead
because of differences in the request & fulfill methods,
but still generate some time delay on a read/write request,
usually about 5% of IDE overhead). But as far as system
overhead goes, you might as well write it off as fait
accompli since there isn't much you can do to alter it
(other than strip out features of the OS: control
panels/extensions under OS 9.2.2 and lower, for example).
And don't call me a propeller head! The term is "technogeek!"
=-= Marc
has wrote:
>
Incidentally, any propeller heads out there know how much,
>
if any, effect other processes on the machine will have on
>
timing accuracy? (I'm assuming that there will always be
>
some variation in timings anyway, due to garbage collection
>
and other unpredictable events occurring within AS itself,
>
but what about everything outside AS?) And if other
>
processes can have an impact, what might be done to lessen
>
that?
_______________________________________________
applescript-users mailing list | email@hidden
Help/Unsubscribe/Archives:
http://www.lists.apple.com/mailman/listinfo/applescript-users
Do not post admin requests to the list. They will be ignored.