Messages in this thread | | | Date | Tue, 07 Jun 2011 11:40:02 +0200 | From | Armin Steinhoff <> | Subject | Re: Changing Kernel thread priorities |
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Hi,
when I read all these confusing statements here ( in german it looks like an "Eiertanz") ... I can only say:
- do the basic stuff in a minimal kernel driver - use UIO (or VFIO for PCI devices)
and you get clean control about your real-time priorities.
I think changing the priorities of "interrupt threads" inside the kernel could lead to strange race conditions in the kernel. That seems to be the reason for that "Eiertanz" here :)
--Armin
Thomas Gleixner wrote: > On Tue, 7 Jun 2011, Johannes Bauer wrote: > > Please stop top-posting and use proper line breaks at 78 > >>> Peter Zijlstra wrote: >>>> "Monica Puig-Pey" wrote: >>>> I need to change the priority from inside the driver, when creating the >>>> kernel thread. >>> No you don't. How does you driver know about what priority is correct >>> wrt all the other running RT tasks on the system? >>> >>> Determining the right priority in a fixed priority scheduling system is >>> a system wide problem, nobody but the administrator can possibly even >>> begin to solve it. >>> >>> There's a reason all RT irq threads are started at 50, its plain >>> impossible to do better. >> Absolutly correct! >> >> However, if you are running the system on an embedded platform, >> where the _WHOLE_ system (including priorities) is preconfigured and >> never touched, starting a irq thread with the right prio from start >> is a more straightforward method than having to invoke a script that >> changes it using userspace chrt tool. > Feel free to do that for your embedded system and carry the patch for > yourself if you think it's worth to avoid the extra init script. > > But we do _not_ add stuff like this to the mainline simply because > there is no way to find a prio setting which is appropriate for all > users of a particular driver. > > Aside of that the extra init script is definitely less annoying to > maintain than the crap you need to hack into random drivers. > > Thanks, > > tglx > -- > To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html >
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