From: Wei Xu <weixugc@google.com>
To: Huang Ying <ying.huang@intel.com>
Cc: Linux MM <linux-mm@kvack.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Keith Busch <kbusch@kernel.org>,
Dave Hansen <dave.hansen@linux.intel.com>,
Yang Shi <shy828301@gmail.com>, Michal Hocko <mhocko@suse.com>,
Zi Yan <ziy@nvidia.com>, David Rientjes <rientjes@google.com>,
Dan Williams <dan.j.williams@intel.com>,
David Hildenbrand <david@redhat.com>
Subject: Re: [PATCH -V9 7/9] mm/vmscan: Consider anonymous pages without swap
Date: Fri, 25 Jun 2021 17:02:25 -0700 [thread overview]
Message-ID: <CAAPL-u8J8A2G=QO24hhn-Em+PXE7Q82OObpPJxNUWznfO-0XRQ@mail.gmail.com> (raw)
In-Reply-To: <20210625073204.1005986-8-ying.huang@intel.com>
On Fri, Jun 25, 2021 at 12:33 AM Huang Ying <ying.huang@intel.com> wrote:
>
> From: Keith Busch <kbusch@kernel.org>
>
> Reclaim anonymous pages if a migration path is available now that
> demotion provides a non-swap recourse for reclaiming anon pages.
>
> Note that this check is subtly different from the
> anon_should_be_aged() checks. This mechanism checks whether a
> specific page in a specific context *can* actually be reclaimed, given
> current swap space and cgroup limits
>
> anon_should_be_aged() is a much simpler and more preliminary check
> which just says whether there is a possibility of future reclaim.
>
> Cc: Keith Busch <kbusch@kernel.org>
> Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
> Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
> Reviewed-by: Yang Shi <shy828301@gmail.com>
> Cc: Michal Hocko <mhocko@suse.com>
> Cc: Zi Yan <ziy@nvidia.com>
> Cc: Wei Xu <weixugc@google.com>
> Cc: David Rientjes <rientjes@google.com>
> Cc: Dan Williams <dan.j.williams@intel.com>
> Cc: David Hildenbrand <david@redhat.com>
>
> --
>
> Changes since 20210618:
> * Consider whether demotion is disabled
>
> Changes from Dave 202010:
> * remove 'total_swap_pages' modification
>
> Changes from Dave 202006:
> * rename reclaim_anon_pages()->can_reclaim_anon_pages()
>
> Note: Keith's Intel SoB is commented out because he is no
> longer at Intel and his @intel.com mail will bounce.
> ---
> mm/vmscan.c | 37 ++++++++++++++++++++++++++++++++++---
> 1 file changed, 34 insertions(+), 3 deletions(-)
>
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index 55f6192b2a51..fce43c7970d7 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -519,6 +519,36 @@ static long add_nr_deferred(long nr, struct shrinker *shrinker,
> return atomic_long_add_return(nr, &shrinker->nr_deferred[nid]);
> }
>
> +static inline bool can_reclaim_anon_pages(struct mem_cgroup *memcg,
> + int node_id,
> + struct scan_control *sc)
> +{
> + if (memcg == NULL) {
> + /*
> + * For non-memcg reclaim, is there
> + * space in any swap device?
> + */
> + if (get_nr_swap_pages() > 0)
> + return true;
> + } else {
> + /* Is the memcg below its swap limit? */
> + if (mem_cgroup_get_nr_swap_pages(memcg) > 0)
> + return true;
> + }
> +
> + /*
> + * The page can not be swapped.
> + *
> + * Can it be reclaimed from this node via demotion?
> + */
> + if ((!sc || !sc->no_demotion) &&
> + next_demotion_node(node_id) != NUMA_NO_NODE)
> + return true;
It is better to abstract these checks into a function, e.g.
can_demote_anon_pages(), to share with anon_can_be_aged().
> + /* No way to reclaim anon pages */
> + return false;
> +}
> +
> /*
> * This misses isolated pages which are not accounted for to save counters.
> * As the data only determines if reclaim or compaction continues, it is
> @@ -530,7 +560,7 @@ unsigned long zone_reclaimable_pages(struct zone *zone)
>
> nr = zone_page_state_snapshot(zone, NR_ZONE_INACTIVE_FILE) +
> zone_page_state_snapshot(zone, NR_ZONE_ACTIVE_FILE);
> - if (get_nr_swap_pages() > 0)
> + if (can_reclaim_anon_pages(NULL, zone_to_nid(zone), NULL))
> nr += zone_page_state_snapshot(zone, NR_ZONE_INACTIVE_ANON) +
> zone_page_state_snapshot(zone, NR_ZONE_ACTIVE_ANON);
>
> @@ -2531,6 +2561,7 @@ enum scan_balance {
> static void get_scan_count(struct lruvec *lruvec, struct scan_control *sc,
> unsigned long *nr)
> {
> + struct pglist_data *pgdat = lruvec_pgdat(lruvec);
> struct mem_cgroup *memcg = lruvec_memcg(lruvec);
> unsigned long anon_cost, file_cost, total_cost;
> int swappiness = mem_cgroup_swappiness(memcg);
> @@ -2541,7 +2572,7 @@ static void get_scan_count(struct lruvec *lruvec, struct scan_control *sc,
> enum lru_list lru;
>
> /* 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, sc)) {
> scan_balance = SCAN_FILE;
> goto out;
> }
> @@ -2916,7 +2947,7 @@ static inline bool should_continue_reclaim(struct pglist_data *pgdat,
> */
> pages_for_compaction = compact_gap(sc->order);
> inactive_lru_pages = node_page_state(pgdat, NR_INACTIVE_FILE);
> - if (get_nr_swap_pages() > 0)
> + if (can_reclaim_anon_pages(NULL, pgdat->node_id, sc))
> inactive_lru_pages += node_page_state(pgdat, NR_INACTIVE_ANON);
>
> return inactive_lru_pages > pages_for_compaction;
> --
> 2.30.2
>
next prev parent reply other threads:[~2021-06-26 0:02 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-25 7:31 [PATCH -V9 0/9] Migrate Pages in lieu of discard Huang Ying
2021-06-25 7:31 ` [PATCH -V9 1/9] mm/numa: add node demotion data structure Huang Ying
2021-06-25 7:31 ` [PATCH -V9 2/9] mm/migrate: update node demotion order during on hotplug events Huang Ying
2021-06-25 21:26 ` Dave Hansen
2021-06-25 7:31 ` [PATCH -V9 3/9] mm/migrate: enable returning precise migrate_pages() success count Huang Ying
2021-06-25 7:31 ` [PATCH -V9 4/9] mm/migrate: demote pages during reclaim Huang Ying
2021-06-26 0:21 ` Wei Xu
2021-06-28 1:52 ` Huang, Ying
2021-06-25 7:32 ` [PATCH -V9 5/9] mm/vmscan: add page demotion counter Huang Ying
2021-06-25 7:32 ` [PATCH -V9 6/9] mm/vmscan: add helper for querying ability to age anonymous pages Huang Ying
2021-06-25 7:32 ` [PATCH -V9 7/9] mm/vmscan: Consider anonymous pages without swap Huang Ying
2021-06-26 0:02 ` Wei Xu [this message]
2021-06-28 2:56 ` Huang, Ying
2021-06-25 7:32 ` [PATCH -V9 8/9] mm/vmscan: never demote for memcg reclaim Huang Ying
2021-06-25 7:32 ` [PATCH -V9 9/9] mm/migrate: add sysfs interface to enable reclaim migration Huang Ying
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