Re: Is there a delay which yields?

--- On Thu, 3/19/09, John Baldwin <jhb_at_freebsd.org> wrote:

> From: John Baldwin <jhb_at_freebsd.org>
> Subject: Re: Is there a delay which yields?
> To: freebsd-current_at_freebsd.org, barney_cordoba_at_yahoo.com
> Cc: "Julian Elischer" <julian_at_elischer.org>, current_at_freebsd.org
> Date: Thursday, March 19, 2009, 11:23 AM
> On Sunday 15 March 2009 2:43:18 pm Barney Cordoba wrote:
> > 
> > --- On Sun, 3/15/09, Julian Elischer
> <julian_at_elischer.org> wrote:
> > 
> > > From: Julian Elischer <julian_at_elischer.org>
> > > Subject: Re: Is there a delay which yields?
> > > To: barney_cordoba_at_yahoo.com
> > > Cc: current_at_freebsd.org
> > > Date: Sunday, March 15, 2009, 1:16 PM
> > > Barney Cordoba wrote:
> > > > I'd expect DELAY to yield till timeout
> but a task
> > > with a delay loop just
> > > > runs to 100% usage. Is there a function
> which can
> > > yield exectution for
> > > > a set amount of time (without having to use
> a timer)?
> > > 
> > > DELAY is designe for use early in the boot when
> thre are no
> > > timers.
> > > it is only occasionally used for cases during
> normal
> > > operation.
> > > 
> > > how would a thread know how long it has been away
> if no
> > > timer is used?
> > 
> > 
> > I guess I mean a sleep. 
> > 
> > Also, this is a kernel driver. I have a device
> > which requires a toggle with a 10ms delay between
> pulses. I hate to 
> > tie up the cpu for 10ms with a delay. Sort of like the
> following:
> > 
> > write_pulse();
> > delay(10000);
> > write_pulse();
> 
> Use pause(9).
>

timo is in hz? So 1/1000th of a second by default?

Also, I notice that hz is 1000 but get 2000 ints/second per
cpu. Why is it twice hz?

Barney