On Tue, Mar 22, 2022 at 1:47 AM Barry Song <21cnbao@xxxxxxxxx> wrote:
>
...
> > +static bool drain_evictable(struct lruvec *lruvec)
> > +{
> > + int gen, type, zone;
> > + int remaining = MAX_LRU_BATCH;
> > +
> > + for_each_gen_type_zone(gen, type, zone) {
> > + struct list_head *head = &lruvec->lrugen.lists[gen][type][zone];
> > +
> > + while (!list_empty(head)) {
> > + bool success;
> > + struct folio *folio = lru_to_folio(head);
> > +
> > + VM_BUG_ON_FOLIO(folio_test_unevictable(folio), folio);
> > + VM_BUG_ON_FOLIO(folio_test_active(folio), folio);
> > + VM_BUG_ON_FOLIO(folio_is_file_lru(folio) != type, folio);
> > + VM_BUG_ON_FOLIO(folio_zonenum(folio) != zone, folio);
> > +
> > + success = lru_gen_del_folio(lruvec, folio, false);
> > + VM_BUG_ON(!success);
> > + lruvec_add_folio(lruvec, folio);
>
> for example, max_seq=4(GEN=0) and max_seq-1=3, then we are supposed to put
> max_seq in the head of active list. but your code seems to be putting max_seq-1
> after putting max_seq, then max_seq is more likely to be evicted
> afterwards as it
> is in the tail of the active list.
This is correct.
> anyway, it might not be so important. I can't imagine we will
> frequently switch mglru
> with lru dynamically. will we?
I certainly hope not :)
