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    SubjectRe: [PATCH] pmac_cpufreq msleep cleanup/fixes
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    On Sat, 2004-10-23 at 08:53, Linus Torvalds wrote:
    > On Sat, 23 Oct 2004, Benjamin Herrenschmidt wrote:
    > >
    > > Please revert that change until we have made absolutely sure that msleep(1)
    > > on a HZ=1000 machine will actually sleep at least 1ms, this is really not
    > > clear since it will end up doing schedule_timeout(1) which, afaik, will
    > > only guarantee to sleep up to the next jiffie, which can be a lot shorter
    > > than the actual duration of a jiffie.
    >
    > In that case I'd much prefer to revert the whole previous "cleanup" as
    > well, since it obviously isn't really. Having
    >
    > msleep(1 + jiffy_to_ms(1));
    >
    > is just not a cleanup to me.

    This wasn't a cleanup but a bug fix actually ... Oh well, I think we need
    to fix msleep() instead, what do you think ? If we keep Nishanth's latest
    cleanup and fix msleep to add +1 to the delay, that would work and potentially
    fix other users as well ... provided my theory is right in the first place
    and that schedule_timeout(1) will indeed only sleep until the next jiffy and
    not for at least one jiffy...

    What about something like this ?

    ---

    Makes sure msleep() sleeps at least the amount provided, since
    schedule_timeout() doesn't guarantee a full jiffy.

    Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

    ===== kernel/timer.c 1.100 vs edited =====
    --- 1.100/kernel/timer.c 2004-10-19 19:40:28 +10:00
    +++ edited/kernel/timer.c 2004-10-23 09:16:10 +10:00
    @@ -1605,7 +1605,7 @@
    */
    void msleep(unsigned int msecs)
    {
    - unsigned long timeout = msecs_to_jiffies(msecs);
    + unsigned long timeout = msecs_to_jiffies(msecs) + 1;

    while (timeout) {
    set_current_state(TASK_UNINTERRUPTIBLE);
    @@ -1621,7 +1621,7 @@
    */
    unsigned long msleep_interruptible(unsigned int msecs)
    {
    - unsigned long timeout = msecs_to_jiffies(msecs);
    + unsigned long timeout = msecs_to_jiffies(msecs) + 1;

    while (timeout && !signal_pending(current)) {
    set_current_state(TASK_INTERRUPTIBLE);

    -
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