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    SubjectRe: 2.7 thoughts
    William Lee Irwin III wrote:
    >> You need at least enough warning to get out of critical sections (e.g.
    >> holding a spinlock) and dump registers out to memory. i.e. as long as it
    >> takes to schedule out whatever's currently running on the thing.
    >> ... and unless you want to start enforcing realtime bounds, the answer
    >> to "how long do you have to give the kernel to do it?" is "forever".
    >> In practice, it won't take forever, but no finite time is enforcible.

    On Fri, Oct 10, 2003 at 04:12:31PM +0100, Jamie Lokier wrote:
    > You can create a very peculiar scheduling state to make even
    > spinlocked sections multi-task, so the CPU can be released in a finite
    > time and quickly - about as quickly as taking an NMI and broadcasting
    > the critical IPIs to tell other CPUs to take over.
    > The peculiar state is restored to normal as soon as the number
    > of concurrent critical sections no longer exceeds the number of real CPUs.

    DOH. Okay, that would do it.


    -- wli
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