Re: [patch] Real-Time Preemption, -RT-2.6.12-rc3-V0.7.46-01

Ingo Molnar
2005-05-04T08:23:43Z

* Lee Revell <rlrevell@joe-job.com> wrote:

> On Fri, 2005-04-22 at 08:27 +0200, Ingo Molnar wrote:
> > i have released the -V0.7.46-01 Real-Time Preemption patch, which can be
> > downloaded from the usual place:
> >
> > http://redhat.com/~mingo/realtime-preempt/
>
> Ingo,
>
> With Mingming's patch to resolve the ext3 allocate-with-reservation
> latency, it looks like we are finally getting close to the lower limit
> that can be achieved with PREEMPT_DESKTOP. I've attached the trace of
> the lowest latency over several days of testing with
> 2.6.12-rc3-RT-V0.7.46-02 + Mingming's patch. It's only 127 usecs, and
> IIRC you mentioned previously that this code path can't be made
> preemptible in !PREEMPT_RT.

yeah, signal delivery will have to stay atomic in !PREEMPT_RT kernels.

> Since Mingming's patch will have to live in -mm for a while, can it be
> added to the RT patchset as well?

i think so - i'll add it to the next patch.

Ingo