From: Michal Hocko <mhocko@suse.com>
To: Muchun Song <songmuchun@bytedance.com>
Cc: hannes@cmpxchg.org, vdavydov.dev@gmail.com,
akpm@linux-foundation.org, shakeelb@google.com, guro@fb.com,
sfr@canb.auug.org.au, alexander.h.duyck@linux.intel.com,
chris@chrisdown.name, laoar.shao@gmail.com,
richard.weiyang@gmail.com, linux-kernel@vger.kernel.org,
cgroups@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [PATCH] mm: memcontrol: optimize per-lruvec stats counter memory usage
Date: Mon, 7 Dec 2020 13:36:05 +0100 [thread overview]
Message-ID: <20201207123605.GH25569@dhcp22.suse.cz> (raw)
In-Reply-To: <20201206085639.12627-1-songmuchun@bytedance.com>
On Sun 06-12-20 16:56:39, Muchun Song wrote:
> The vmstat threshold is 32 (MEMCG_CHARGE_BATCH), so the type of s32
> of lruvec_stat_cpu is enough. And introduce struct per_cpu_lruvec_stat
> to optimize memory usage.
How much savings are we talking about here? I am not deeply familiar
with the pcp allocator but can it compact smaller data types much
better?
> Signed-off-by: Muchun Song <songmuchun@bytedance.com>
> ---
> include/linux/memcontrol.h | 6 +++++-
> mm/memcontrol.c | 2 +-
> 2 files changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
> index f9a496c4eac7..34cf119976b1 100644
> --- a/include/linux/memcontrol.h
> +++ b/include/linux/memcontrol.h
> @@ -92,6 +92,10 @@ struct lruvec_stat {
> long count[NR_VM_NODE_STAT_ITEMS];
> };
>
> +struct per_cpu_lruvec_stat {
> + s32 count[NR_VM_NODE_STAT_ITEMS];
> +};
> +
> /*
> * Bitmap of shrinker::id corresponding to memcg-aware shrinkers,
> * which have elements charged to this memcg.
> @@ -111,7 +115,7 @@ struct mem_cgroup_per_node {
> struct lruvec_stat __percpu *lruvec_stat_local;
>
> /* Subtree VM stats (batched updates) */
> - struct lruvec_stat __percpu *lruvec_stat_cpu;
> + struct per_cpu_lruvec_stat __percpu *lruvec_stat_cpu;
> atomic_long_t lruvec_stat[NR_VM_NODE_STAT_ITEMS];
>
> unsigned long lru_zone_size[MAX_NR_ZONES][NR_LRU_LISTS];
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index 49fbcf003bf5..c874ea37b05d 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -5184,7 +5184,7 @@ static int alloc_mem_cgroup_per_node_info(struct mem_cgroup *memcg, int node)
> return 1;
> }
>
> - pn->lruvec_stat_cpu = alloc_percpu_gfp(struct lruvec_stat,
> + pn->lruvec_stat_cpu = alloc_percpu_gfp(struct per_cpu_lruvec_stat,
> GFP_KERNEL_ACCOUNT);
> if (!pn->lruvec_stat_cpu) {
> free_percpu(pn->lruvec_stat_local);
> --
> 2.11.0
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2020-12-07 12:36 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-06 8:56 [PATCH] mm: memcontrol: optimize per-lruvec stats counter memory usage Muchun Song
2020-12-07 12:36 ` Michal Hocko [this message]
2020-12-07 12:56 ` [External] " Muchun Song
2020-12-07 15:09 ` Michal Hocko
2020-12-07 15:19 ` Muchun Song
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