(cc memcg developers)
On Thu, 23 Jun 2022 16:01:03 +0800 zhouchuyi <zhouchuyi@xxxxxxxxxxxxx> wrote:
> Add pgstall to indicate the times of entering direct reclaim of memcg, use
> the item of ALLOCSTALL_NORMAL in vmevents to save the data.
>
> Signed-off-by: zhouchuyi <zhouchuyi@xxxxxxxxxxxxx>
> ---
>
>
> Hi，
>
> I notice memcg uses some items to indicate the situation of direct reclaim in memory.stat，such as pgsteal and pgscan.
> I think there is no harm in adding another item to show the times of entering direct reclaim.
>
Why do you consider this useful? Do you have a use case? If so,
please describe it in detail.
>
> ...
>
> diff --git a/Documentation/admin-guide/cgroup-v2.rst b/Documentation/admin-guide/cgroup-v2.rst
> index 176298f2f..44c5b15bd 100644
> --- a/Documentation/admin-guide/cgroup-v2.rst
> +++ b/Documentation/admin-guide/cgroup-v2.rst
> @@ -1447,8 +1447,11 @@ PAGE_SIZE multiple when read back.
>
> pgsteal (npn)
> Amount of reclaimed pages
> -
> - pgactivate (npn)
> +
> + pgstall (npn)
> + Number of entering direct reclaim
> +
> + pgactivate (npn)
> Amount of pages moved to the active LRU list
>
> pgdeactivate (npn)
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index abec50f31..f407084b2 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -1505,6 +1505,8 @@ static char *memory_stat_format(struct mem_cgroup *memcg)
> seq_buf_printf(&s, "pgscan %lu\n",
> memcg_events(memcg, PGSCAN_KSWAPD) +
> memcg_events(memcg, PGSCAN_DIRECT));
> + seq_buf_printf(&s, "pgstall %lu\n",
> + memcg_events(memcg, ALLOCSTALL_NORMAL));
> seq_buf_printf(&s, "pgsteal %lu\n",
> memcg_events(memcg, PGSTEAL_KSWAPD) +
> memcg_events(memcg, PGSTEAL_DIRECT));
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index f7d9a683e..107cec59a 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -3532,7 +3532,10 @@ static unsigned long do_try_to_free_pages(struct zonelist *zonelist,
>
> if (!cgroup_reclaim(sc))
> __count_zid_vm_events(ALLOCSTALL, sc->reclaim_idx, 1);
> -
> + else {
> + count_memcg_events(sc->target_mem_cgroup,
> + ALLOCSTALL_NORMAL, 1);
> + }
> do {
> vmpressure_prio(sc->gfp_mask, sc->target_mem_cgroup,
> sc->priority);
> --
> 2.20.1
