On Wed, 28 Sep 2005, Simon White wrote:
> Hi,
>
> Wondered if anyone could provide information about where to look for
> suitable kernel timers?
Have you taken a look at what is being done by Thomas Gleixner?
http://lwn.net/Articles/152363/
Also you may be interested in Ingo Molnar's RT kernel.
http://people.redhat.com/mingo/realtime-preempt/
As well as the work being done by the HRT folks.
http://sourceforge.net/projects/high-res-timers
-- Steve
>
> For a while I have been working on supporting the hardsid/catweasel
> cards on Linux (and Windows). Although undesirable the original
> implementations required real usec delays in the OS
> (this requirement being fixed in the very latest hardware). I know
> Linux is not realtime so the original drivers were designed to
> queue hardware writes to a realtime thread that busy waited and
> recovered as best it could from errors (on the whole this worked
> pretty well). Also another version of the code was written to use
> rtlinux/rtai that was capable of non busy waiting.
>
> More recently with the release of the new buffering hardware the
> driver was redesigned from the realtime posix code. Due to these
> changes the busy waiting (for the old cards) can nolonger occur
> and the delays have to happen asynchronusly notifing the realtime
> thread when the delay has expired. The code uses the posix
> timer_set, etc calls with realtime clock with absolute delays and
> flags a semaphore when the signal occurs (works great under
> realtime systems).
>
> Now as an alternative it is again desired that a version (although
> wont perfectly work) be available to a vanilla 2.6 kernel (possibly
> 2.4) with similiar limitations as before. Its a shame the posix
> calls appear to not be supported in kernel for drivers so I have
> wrapped the calls for semaphores/mutexs/threads to kernel
> equivalents.
>
> However I have no idea what to do for the timers. Is there
> something suitable inkernel that would provide an async callback
> to pre-empt a realtime thread and provide better resolution than
> HZ a far amount of the time? Or do I have to run a seperate lower
> priority busy waiting thread to wakeup the realtime one?
>
> Advice appreciated.
> Simon
>
> --
> ___________________________________________________________
> Sign-up for Ads Free at Mail.com
> http://promo.mail.com/adsfreejump.htm
>
> -
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to [email protected]
> More majordomo info at http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at http://www.tux.org/lkml/
>
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[Index of Archives]
[Kernel Newbies]
[Netfilter]
[Bugtraq]
[Photo]
[Gimp]
[Yosemite News]
[MIPS Linux]
[ARM Linux]
[Linux Security]
[Linux RAID]
[Video 4 Linux]
[Linux for the blind]
| |
 |