Re: [RFC][PATCH 11/13] mm/vmscan: Consider anonymous pages without swap

[Yang Shi]

On Tue, Feb 2, 2021 at 1:35 PM Dave Hansen <dave.hansen@xxxxxxxxx> wrote:
>
> On 2/2/21 10:56 AM, Yang Shi wrote:
> >>
> >>         /* If we have no swap space, do not bother scanning anon pages. */
> >> -       if (!sc->may_swap || mem_cgroup_get_nr_swap_pages(memcg) <= 0) {
> >> +       if (!sc->may_swap || !can_reclaim_anon_pages(memcg, pgdat->node_id)) {
> > Just one minor thing about may_swap. It may be cleared by
> > nr_boost_reclaim. But demotion should be fine for boost_reclaim.
>
> In other words, this if() is here is to avoid generating suboptimal I/O
> during boost_reclaim.  But, since demotion doesn't generate any I/O, it
> *should* be fine for boost_reclaim.
>
> I agree with that in theory.  Although, I'm tempted to put it in the
> TODO list as something to look at in the future.  Do you think it's
> something that's immediately necessary?

No, I don't think so. We could tweak this later on.