On 05/02/2021 12:48, Vincent Guittot wrote: > Instead of waking up a random and already idle CPU, we can take advantage > of this_cpu being about to enter idle to run the ILB and update the > blocked load. > > Signed-off-by: Vincent Guittot <[email protected]> > --- > include/linux/sched/nohz.h | 2 ++ > kernel/sched/fair.c | 11 ++++++++--- > kernel/sched/idle.c | 6 ++++++ > 3 files changed, 16 insertions(+), 3 deletions(-) > > diff --git a/include/linux/sched/nohz.h b/include/linux/sched/nohz.h > index 6d67e9a5af6b..74cdc4e87310 100644 > --- a/include/linux/sched/nohz.h > +++ b/include/linux/sched/nohz.h > @@ -9,8 +9,10 @@ > #if defined(CONFIG_SMP) && defined(CONFIG_NO_HZ_COMMON) > extern void nohz_balance_enter_idle(int cpu); > extern int get_nohz_timer_target(void); > +extern void nohz_run_idle_balance(int cpu); > #else > static inline void nohz_balance_enter_idle(int cpu) { } > +static inline void nohz_run_idle_balance(int cpu) { } > #endif
(1) Since nohz_run_idle_balance() would be an interface one sched class (fair) exports to another (idle) I wonder if kernel/sched/sched.h would be the more appropriate include file to export/define it? nohz_balance_exit_idle() is exported via kernel/sched/sched.h (used only within the scheduler) whereas nohz_balance_enter_idle() is exported via include/linux/sched/nohz.h (used in kernel/time/tick-sched.c). Isn't include/linux/sched/nohz.h the interface between kernel/sched/ and kernel/time? There is one exception already though: calc_load_nohz_remote() defined in kernel/sched/loadavg.c and (only) used in kernel/sched/core.c. (2) Is there a need for an extra function nohz_run_idle_balance()? do_idle() could call nohz_idle_balance() directly in case in would be exported instead. [...]
