Re: [patch] Real-Time Preemption, -RT-2.6.12-rc1-V0.7.43-00

Zwane Mwaikambo
2005-04-04T22:56:49Z

On Mon, 4 Apr 2005, Steven Rostedt wrote:

> On Mon, 2005-04-04 at 22:47 +0200, Ingo Molnar wrote:
>
> > > Currently my fix is in yield to lower the priority of the task calling
> > > yield and raise it after the schedule. This is NOT a proper fix. It's
> > > just a hack so I can get by it and test other parts.
> >
> > yeah, yield() is a quite RT-incompatible concept, which could livelock
> > an upstream kernel just as much - if the task in question is SCHED_FIFO.
> > Almost all yield() uses should be eliminated from the upstream kernel,
> > step by step.
>
> Now the question is, who will fix it? Preferably the maintainers, but I
> don't know how much of a priority this is to them. I don't have the time
> now to look at this and understand enough about the code to be able to
> make a proper fix, and I'm sure you have other things to do too.

I'm sure a lot of the yield() users could be converted to
schedule_timeout(), some of the users i saw were for low memory conditions
where we want other tasks to make progress and complete so that we a bit
more free memory.