On 06/11/2015 11:06 PM, Frederic Weisbecker wrote: > This is a leftover from old days to avoid conflicts with dynticks idle > code. Now full dynticks and idle dynticks are better integrated and > interact without known issue.
I am sorry but I fail to understand why the check on idle task was there in the first place in the below code paths. It would help if you could clarify this in the changelog as well. > > So lets remove it. > > Cc: Christoph Lameter <[email protected]> > Cc: Ingo Molnar <[email protected]> > Cc; John Stultz <[email protected]> > Cc: Peter Zijlstra <[email protected]> > Cc: Preeti U Murthy <[email protected]> > Cc: Rik van Riel <[email protected]> > Cc: Thomas Gleixner <[email protected]> > Cc: Viresh Kumar <[email protected]> > Signed-off-by: Frederic Weisbecker <[email protected]> > --- > kernel/time/tick-sched.c | 8 +++----- > 1 file changed, 3 insertions(+), 5 deletions(-) > > diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c > index 812f7a3..324482f 100644 > --- a/kernel/time/tick-sched.c > +++ b/kernel/time/tick-sched.c > @@ -208,10 +208,8 @@ void __tick_nohz_full_check(void) > struct tick_sched *ts = this_cpu_ptr(&tick_cpu_sched); > > if (tick_nohz_full_cpu(smp_processor_id())) { > - if (ts->tick_stopped && !is_idle_task(current)) { > - if (!can_stop_full_tick()) can_stop_full_tick() would have bailed out if the current task was idle, since it checks for the number of tasks being greater than 1 to restart the tick. So why was the check is_idle_task() introduced earlier ? > - tick_nohz_restart_sched_tick(ts, ktime_get()); > - } > + if (ts->tick_stopped && !can_stop_full_tick()) > + tick_nohz_restart_sched_tick(ts, ktime_get()); > } > } > > @@ -710,7 +708,7 @@ static void tick_nohz_full_stop_tick(struct tick_sched > *ts) > #ifdef CONFIG_NO_HZ_FULL > int cpu = smp_processor_id(); > > - if (!tick_nohz_full_cpu(cpu) || is_idle_task(current)) > + if (!tick_nohz_full_cpu(cpu)) If the current task was indeed idle, the check on ts->inidle would have succeeded in tick_irq_exit() and we would not have reached this function at all, isn't it? So here too I am unable to understand why we had it in the first place. Regards Preeti U Murthy > return; > > if (!ts->tick_stopped && ts->nohz_mode == NOHZ_MODE_INACTIVE) > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
