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    From
    SubjectRe: nohz and strange sleep latencies
    Date
    On Saturday, 24 of November 2007, Pavel Machek wrote:
    > Hi!
    >
    > > > > but perhaps somehow we miss this fact and fail to turn off the lapic
    > > > > clockevents drivers?
    > > >
    > > > Ok, I guess I'm lost. If I offline second CPU, I immediately get
    > > > 1000Hz timer tick... is that expected?
    > >
    > > Hmm. No. I have no idea why this is happening.
    > >
    > > 34196 total events, 55.083 events/sec
    > > echo 0 >/sys/devices/system/cpu/cpu1/online
    > > 36073 total events, 54.679 events/sec
    >
    > Digging into process_32|64.c...
    >
    > 64:
    > while (1) {
    > while (!need_resched()) {
    > void (*idle)(void);
    >
    > if (__get_cpu_var(cpu_idle_state))
    > __get_cpu_var(cpu_idle_state) = 0;
    >
    > tick_nohz_stop_sched_tick();
    >
    > 32:
    > while (1) {
    > tick_nohz_stop_sched_tick();
    > while (!need_resched()) {
    > void (*idle)(void);
    >
    > if (__get_cpu_var(cpu_idle_state))
    > __get_cpu_var(cpu_idle_state) = 0;
    >
    > ...eek? Which one is wrong?

    Hm, it looks like you should have quoted more lines ...

    In the second case (32), the tick_nohz_stop_sched_tick() seems to be
    redundant, so I bet it's this one.

    Greetings,
    Rafael
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