synth specific settings. was: delaytime of litetalk driver

[Kirk Reiser]

It has become quite popular to play with these settings since Frank
discovered them a few days ago.  You all may have noticed that you
need to be root to make changes to these settings.  The reason for
that, and there is a reason, is that they can fuck up your system big
time if you're not careful.  The common consensus is well okay
sometimes they may hang my system and I'll have to reboot; well they
can have much more violent reactions than that.  If they are set to
far a field they can infact currupt your file system.  Okay you've
been warned.

Let's just get the functions of these variables straight.  Delay_time
is the amount of time that speakup goes to sleep after sending
characters to the synth.  Speakup sends out jiffy_delta worth of
characters before going to sleep for delay_time.  Speakup does not
start talking to the synth until trigger_time worth of characters have
been sent to the buffer.  Trigger_time is a one-shot in that it
doesn't get set again until the buffer has been cleared.  Jiffy_delta
is the amount of time speakup holds the kernel while sending
characters to the synth.  A word about these values, delay_time,
trigger_time and full_time are in miliseconds.  Jiffy_delta is in ten
milisecond increments.  So a trigger_time of 50 is the same as five
jiffies.  Jiffies are the basic scheduling increment of Linux on
32-bit processors they are ten miliseconds.  On systems such as alphas
and sparcs they are one milisecond.  The higher jiffy_delta is the
longer you hold the processor.  This wouldn't be bad except that we're
talking multitasking here, so what you take someone else doesn't get
in any given time period.  We can go into a rather indepth discussion
about interrupts and all that but I'd rather save that for the
reflector if anyone is interested.  The bottom line is you grab to
much time and you'll have a totally fucked file system, network layer
and who knows what else.  So be careful.

The default values are not optimal because of the amount of time I
have to spend with each synth.  Some drivers I never even have the
synth to test with.  We have already incorporated some of the new
values that people like Frank and Bill have come up with.  Over time
we will hopefully be able to tune all the different synths.  I just
want you to  know what you are dealing with if you are going to muck
about.  I was worried because it looks to me as if you didn't know
what these values are for Chris.

So you've all been warned.  If you fuck your systems over don't even
bother mentioning it to me.  meanwhile happy tuning.  If you get better
values for your synths please post them to the list and on the
reflector.

  Kirk

-- 

Kirk Reiser				The Computer Braille Facility
e-mail: kirk at braille.uwo.ca		University of Western Ontario
phone: (519) 661-3061