Li Zhijian <lizhijian@xxxxxxxxxxx> writes:
> pgdemote_src_*: pages demoted from this node.
> pgdemote_dst_*: pages demoted to this node.
>
> So that we are able to know their demotion per-node stats by checking this.
>
> In the environment, node0 and node1 are DRAM, node3 is PMEM.
>
> Global stats:
> $ grep -E 'demote' /proc/vmstat
> pgdemote_src_kswapd 130155
> pgdemote_src_direct 113497
> pgdemote_src_khugepaged 0
> pgdemote_dst_kswapd 130155
> pgdemote_dst_direct 113497
> pgdemote_dst_khugepaged 0
>
> Per-node stats:
> $ grep demote /sys/devices/system/node/node0/vmstat
> pgdemote_src_kswapd 68454
> pgdemote_src_direct 83431
> pgdemote_src_khugepaged 0
> pgdemote_dst_kswapd 0
> pgdemote_dst_direct 0
> pgdemote_dst_khugepaged 0
>
> $ grep demote /sys/devices/system/node/node1/vmstat
> pgdemote_src_kswapd 185834
> pgdemote_src_direct 30066
> pgdemote_src_khugepaged 0
> pgdemote_dst_kswapd 0
> pgdemote_dst_direct 0
> pgdemote_dst_khugepaged 0
>
> $ grep demote /sys/devices/system/node/node3/vmstat
> pgdemote_src_kswapd 0
> pgdemote_src_direct 0
> pgdemote_src_khugepaged 0
> pgdemote_dst_kswapd 254288
> pgdemote_dst_direct 113497
> pgdemote_dst_khugepaged 0
>
> From above stats, we know node3 is the demotion destination which one
> the node0 and node1 will demote to.
Why do we need these information? Do you have some use case?
--
Best Regards,
Huang, Ying
> Signed-off-by: Li Zhijian <lizhijian@xxxxxxxxxxx>
> ---
> RFC: their names are open to discussion, maybe pgdemote_from/to_*
> Another defect of this patch is that, SUM(pgdemote_src_*) is always same
> as SUM(pgdemote_dst_*) in the global stats, shall we hide one of them.
> ---
> include/linux/mmzone.h | 9 ++++++---
> mm/vmscan.c | 13 ++++++++++---
> mm/vmstat.c | 9 ++++++---
> 3 files changed, 22 insertions(+), 9 deletions(-)
>
> diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
> index ad0309eea850..a6140d894bec 100644
> --- a/include/linux/mmzone.h
> +++ b/include/linux/mmzone.h
> @@ -207,9 +207,12 @@ enum node_stat_item {
> PGPROMOTE_SUCCESS, /* promote successfully */
> PGPROMOTE_CANDIDATE, /* candidate pages to promote */
> /* PGDEMOTE_*: pages demoted */
> - PGDEMOTE_KSWAPD,
> - PGDEMOTE_DIRECT,
> - PGDEMOTE_KHUGEPAGED,
> + PGDEMOTE_SRC_KSWAPD,
> + PGDEMOTE_SRC_DIRECT,
> + PGDEMOTE_SRC_KHUGEPAGED,
> + PGDEMOTE_DST_KSWAPD,
> + PGDEMOTE_DST_DIRECT,
> + PGDEMOTE_DST_KHUGEPAGED,
> #endif
> NR_VM_NODE_STAT_ITEMS
> };
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index 2f1fb4ec3235..55d2287d7150 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -1111,13 +1111,18 @@ void drop_slab(void)
> static int reclaimer_offset(void)
> {
> BUILD_BUG_ON(PGSTEAL_DIRECT - PGSTEAL_KSWAPD !=
> - PGDEMOTE_DIRECT - PGDEMOTE_KSWAPD);
> + PGDEMOTE_SRC_DIRECT - PGDEMOTE_SRC_KSWAPD);
> BUILD_BUG_ON(PGSTEAL_DIRECT - PGSTEAL_KSWAPD !=
> PGSCAN_DIRECT - PGSCAN_KSWAPD);
> BUILD_BUG_ON(PGSTEAL_KHUGEPAGED - PGSTEAL_KSWAPD !=
> - PGDEMOTE_KHUGEPAGED - PGDEMOTE_KSWAPD);
> + PGDEMOTE_SRC_KHUGEPAGED - PGDEMOTE_SRC_KSWAPD);
> BUILD_BUG_ON(PGSTEAL_KHUGEPAGED - PGSTEAL_KSWAPD !=
> PGSCAN_KHUGEPAGED - PGSCAN_KSWAPD);
> + BUILD_BUG_ON(PGDEMOTE_SRC_DIRECT - PGDEMOTE_SRC_KSWAPD !=
> + PGDEMOTE_DST_DIRECT - PGDEMOTE_DST_KSWAPD);
> + BUILD_BUG_ON(PGDEMOTE_SRC_KHUGEPAGED - PGDEMOTE_SRC_KSWAPD !=
> + PGDEMOTE_DST_KHUGEPAGED - PGDEMOTE_DST_KSWAPD);
> +
>
> if (current_is_kswapd())
> return 0;
> @@ -1678,8 +1683,10 @@ static unsigned int demote_folio_list(struct list_head *demote_folios,
> (unsigned long)&mtc, MIGRATE_ASYNC, MR_DEMOTION,
> &nr_succeeded);
>
> + mod_node_page_state(pgdat,
> + PGDEMOTE_SRC_KSWAPD + reclaimer_offset(), nr_succeeded);
> mod_node_page_state(NODE_DATA(target_nid),
> - PGDEMOTE_KSWAPD + reclaimer_offset(), nr_succeeded);
> + PGDEMOTE_DST_KSWAPD + reclaimer_offset(), nr_succeeded);
>
> return nr_succeeded;
> }
> diff --git a/mm/vmstat.c b/mm/vmstat.c
> index f141c48c39e4..63f106a5e008 100644
> --- a/mm/vmstat.c
> +++ b/mm/vmstat.c
> @@ -1244,9 +1244,12 @@ const char * const vmstat_text[] = {
> #ifdef CONFIG_NUMA_BALANCING
> "pgpromote_success",
> "pgpromote_candidate",
> - "pgdemote_kswapd",
> - "pgdemote_direct",
> - "pgdemote_khugepaged",
> + "pgdemote_src_kswapd",
> + "pgdemote_src_direct",
> + "pgdemote_src_khugepaged",
> + "pgdemote_dst_kswapd",
> + "pgdemote_dst_direct",
> + "pgdemote_dst_khugepaged",
> #endif
>
> /* enum writeback_stat_item counters */
