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    SubjectRe: [patch] Real-Time Preemption, -RT-2.6.10-rc2-mm3-V0.7.32-6
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    On Thu, 2004-12-09 at 10:32 +0100, Ingo Molnar wrote:
    > * Steven Rostedt <rostedt@goodmis.org> wrote:
    > > Ingo really scares me with all the removing of local_irq_disables in
    > > the rt mode. I'm not sure exactly what is going on there, and why they
    > > can, or should be removed. Ingo?
    >
    > it is done so that the SLAB code can be fully preempted too. The SLAB
    > code is of central importance to the -RT project, if it's not fully
    > preemptible then that has a ripple effect on other subsystems (timer,
    > signal code, file handling, etc.).
    >
    > So while making it fully preemptible was quite challenging (==dangerous,
    > scary), i couldnt just keep the SLAB using raw spinlocks, due to the
    > locking dependencies. (nor did i have any true inner desire to keep it
    > non-preemptible - the point of PREEMPT_RT is to have everything
    > preemptible. I want to see how much preemption the Linux kernel can take
    > =B-) It has held up surprisingly well i have to say.)

    <snip>


    >
    > Ingo


    Ingo,

    Thanks for the write up. It really clears things up for me. Now I
    understand your approach, not only for slabs, but other areas of the
    kernel. Once again, thanks for the explanation.

    -- Steve

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