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    SubjectRe: looking for info on kernel_thread
    On Mon, Apr 12, 1999 at 12:20:29PM -0400, Jason A. Pfeil wrote:
    > kernel_thread is used to create the kernel-level processes like kswapd,
    > bdflush, and others. I would tend to think that it is preemptable like
    > any other process, but I could be wrong. Feel free to correct me. :)

    I am not sure if this is a valid test for preemptableness (word?), but
    I started a kernel thread in init/main.c for spind:

    void spind(void)
    unsigned int spinner;

    Console showed a steady stream of "wrapped" and didn't make any other

    I have the bottom half handler running as a kernel thread on another
    box and it doesn't seem to have any trouble - but that chunk of code
    is structured to sleep on a semaphore until the scheduler wakes it
    up (ie the bh handler volunteers to give up the cpu when it figures
    it has done enough - no preemption required.) I will eventually be
    getting to the question of whether bottom halves can handle being
    preempted. I kind of expected the box to crash but it ran under
    heavy load for 48 hours. I would have to guess then that the semantics
    of kernel_thread are such that I effectively "did nothing" by
    stuffing the bottom half handler into its own thread.

    learning slowly...


    ps. As a newbie to the list, let me know if this stuff is off topic
    or should be posted elsewhere.

    > On Mon, 12 Apr 1999 wrote:
    > > I am looking for some details about kernel threads.
    > > I see kernel_thread defined in arch/whatever/kernel/,
    > > but I am not totally clear on the details of how it
    > > works. Specifically, how is it scheduled? Is it
    > > preemptable? (my guess is no.)
    > >
    > > Is there a doc/book available with any details?
    > >
    > > thanks.
    > >
    > > pete
    > >
    > >
    > > -
    > > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    > > the body of a message to
    > > Please read the FAQ at
    > >
    > ----
    > Jason A. Pfeil
    > Network Administrator
    > CASDL (850)644-8014; fax: (850)644-4952
    > Learning Systems Institute University Center C-3519
    > Tallahassee, FL 32306-2540

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