Is there a delay which yields?

[Julian Elischer]

Barney Cordoba wrote:
> 
> 
> 
> --- 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?

how many cpus do you have?

> 
> Barney
> 
> 
>       
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