Subj : Re: NPTL, linuxthreads, and posix periodic timers (time shift)
To   : comp.programming.threads
From : =?ISO-8859-15?Q?st=E9phane_SARAGAGLIA?=
Date : Wed Jan 05 2005 11:30 am

David Schwartz wrote:

>>I would like to use NPTL, but the results displayed by DISPLAY2 are
>>alarming me...
>>I have tried using 2.6.7 and 2.6.9 kernels, and I obtain the same 
>>results...
> 
>     I think you're trying to rely on something that's not guaranteed.
>
>>Why such a difference between 2.6 and 2.4 kernel ?
> 
>     Because you're relying on something that's not guaranteed, so nobody 
> cares if it changes.

Ok. So what is guaranteed ? The fact that the timer event will occur AT 
LEAST AFTER the it_interval value specified ? Never less than 
it_interval value ?

>>Are posix timers not suitable to my needs ?
> 
>     They are not suitable as they are coded. You should wrap them with code 
> that provides the precise guarantees that you require.

I am surprised there is no easy way to set up a periodic timer whose 
goal is to be consistent to start tick.
How would you wrap posix timers ? By starting a one shot timer, then 
reading the overrun time and starting another one shorter ?

Thank you for your explanation !

Regards

.