[Asterisk-Dev] MeetMe with SMP and no USB

[Matthew Boehm]

Why is it that most of the other app_*.so programs don't need this hardware
clock? What is so special about MeetMe that it 'DOES' need a hardware clock?

Matthew
----- Original Message ----- 
From: "Tilghman Lesher" <tilghman at mail.jeffandtilghman.com>
To: "Asterisk Developers Mailing List" <asterisk-dev at lists.digium.com>
Sent: Thursday, September 09, 2004 12:36 PM
Subject: Re: [Asterisk-Dev] MeetMe with SMP and no USB


> On Thursday 09 September 2004 06:47, Gilad Ben-Yossef wrote:
> > Moaning and complaining aside :-) I know (because I've done and it
> > works) that one can easily change the definition of HZ macro of the
> > Linux kernel (param.h) from it's default of 100 (on x86) to 1000, thus
> > setting regular timer tick of Linux to 1000Hz.
> >
> > In fact, in 2.6 I believe that 1000 is even the default value as well as
> > being the defult value on PPC and Alpha.
>
> In 2.6, the default for i386 is still 100, although the location of the
> definition seems to be <asm/param.h>.  PPC default is also 100.  Alpha
> default seems to be either 1024 or 1200, depending upon the hardware.
>
> > So, assuming the regular timer tick of the system is of 1000Hz, does an
> > outside timing source is really required?
>
> The problem is that this software tick is approximate and does not provide
> the rigid 1/1000 tick that is needed.  Each sample would therefore not
always
> be the same length (some short of 1/1000th, some longer than that period),
so
> your audio would be imperfect.  How imperfect it would be would depend
upon
> the actual system hardware and the current system load.
>
> -- 
> Tilghman
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