On Wed, 24 Nov 2021 13:42:10 -0800 Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> wrote:
> On Wed, 24 Nov 2021 14:52:19 +0000 SeongJae Park <sj@xxxxxxxxxx> wrote:
>
> > Because DAMON sleeps in uninterruptible mode, /proc/loadavg reports fake
> > load while DAMON is turned on, though it is doing nothing. This can
> > confuse users[1]. To avoid the case, this commit makes DAMON sleeps in
> > idle mode.
> >
> > --- a/mm/damon/core.c
> > +++ b/mm/damon/core.c
> > @@ -12,6 +12,8 @@
> > #include <linux/kthread.h>
> > #include <linux/mm.h>
> > #include <linux/random.h>
> > +#include <linux/sched.h>
> > +#include <linux/sched/debug.h>
> > #include <linux/slab.h>
> > #include <linux/string.h>
> >
> > @@ -976,12 +978,25 @@ static unsigned long damos_wmark_wait_us(struct damos *scheme)
> > return 0;
> > }
> >
> > +/* sleep for @usecs in idle mode */
> > +static void __sched damon_usleep_idle(unsigned long usecs)
> > +{
> > + ktime_t exp = ktime_add_us(ktime_get(), usecs);
> > + u64 delta = usecs * NSEC_PER_USEC / 100; /* allow 1% error */
> > +
> > + for (;;) {
> > + __set_current_state(TASK_IDLE);
> > + if (!schedule_hrtimeout_range(&exp, delta, HRTIMER_MODE_ABS))
> > + break;
> > + }
> > +}
>
> Let's not copy-n-paste usleep_range() into damon code?
>
> A new usleep_idle_range() in kernel/time/timer.c seems like a
> worthwhile addition. Perhaps usleep_idle_range() and usleep_range()
> can be static inline wrappers against a new, more general function in
> kernel/time/timer.c - usleep_range_state(min, max, state)?
Makes sense, agreed. I will post next version soon.
Thanks,
SJ
