On Mon 05-08-19 13:04:50, Joel Fernandes (Google) wrote: > During idle tracking, we see that sometimes faulted anon pages are in > pagevec but are not drained to LRU. Idle tracking considers pages only > on LRU. Drain all CPU's LRU before starting idle tracking.
Please expand on why does this matter enough to introduce a potentially expensinve draining which has to schedule a work on each CPU and wait for them to finish. > Signed-off-by: Joel Fernandes (Google) <j...@joelfernandes.org> > --- > mm/page_idle.c | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/mm/page_idle.c b/mm/page_idle.c > index a5b00d63216c..2972367a599f 100644 > --- a/mm/page_idle.c > +++ b/mm/page_idle.c > @@ -180,6 +180,8 @@ static ssize_t page_idle_bitmap_read(struct file *file, > struct kobject *kobj, > unsigned long pfn, end_pfn; > int bit, ret; > > + lru_add_drain_all(); > + > ret = page_idle_get_frames(pos, count, NULL, &pfn, &end_pfn); > if (ret == -ENXIO) > return 0; /* Reads beyond max_pfn do nothing */ > @@ -211,6 +213,8 @@ static ssize_t page_idle_bitmap_write(struct file *file, > struct kobject *kobj, > unsigned long pfn, end_pfn; > int bit, ret; > > + lru_add_drain_all(); > + > ret = page_idle_get_frames(pos, count, NULL, &pfn, &end_pfn); > if (ret) > return ret; > @@ -428,6 +432,8 @@ ssize_t page_idle_proc_generic(struct file *file, char > __user *ubuff, > walk.private = &priv; > walk.mm = mm; > > + lru_add_drain_all(); > + > down_read(&mm->mmap_sem); > > /* > -- > 2.22.0.770.g0f2c4a37fd-goog -- Michal Hocko SUSE Labs
