From: Michal Hocko <mhocko@suse.com>
To: Miaohe Lin <linmiaohe@huawei.com>
Cc: hannes@cmpxchg.org, roman.gushchin@linux.dev,
shakeelb@google.com, akpm@linux-foundation.org,
cgroups@vger.kernel.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] mm/memcg: remove unneeded nr_scanned
Date: Mon, 28 Mar 2022 14:01:32 +0200 [thread overview]
Message-ID: <YkGjnAOidFD8bA3a@dhcp22.suse.cz> (raw)
In-Reply-To: <20220328114144.53389-1-linmiaohe@huawei.com>
On Mon 28-03-22 19:41:44, Miaohe Lin wrote:
> The local variable nr_scanned is unneeded as mem_cgroup_soft_reclaim always
> does *total_scanned += nr_scanned. So we can pass total_scanned directly to
> the mem_cgroup_soft_reclaim to simplify the code and save some cpu cycles
> of adding nr_scanned to total_scanned.
Maybe the compiler could be clever enough to generate a good code.
mem_cgroup_soft_reclaim doesn't have other caller so it could be
inlined. But I do agree that the change makes sense because it makes the
code more consistent as mem_cgroup_soft_limit_reclaim already uses
total_scanned this way.
> Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Thanks
> ---
> mm/memcontrol.c | 5 +----
> 1 file changed, 1 insertion(+), 4 deletions(-)
>
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index b686ec4f42c6..79341365ec90 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -3384,7 +3384,6 @@ unsigned long mem_cgroup_soft_limit_reclaim(pg_data_t *pgdat, int order,
> int loop = 0;
> struct mem_cgroup_tree_per_node *mctz;
> unsigned long excess;
> - unsigned long nr_scanned;
>
> if (order > 0)
> return 0;
> @@ -3412,11 +3411,9 @@ unsigned long mem_cgroup_soft_limit_reclaim(pg_data_t *pgdat, int order,
> if (!mz)
> break;
>
> - nr_scanned = 0;
> reclaimed = mem_cgroup_soft_reclaim(mz->memcg, pgdat,
> - gfp_mask, &nr_scanned);
> + gfp_mask, total_scanned);
> nr_reclaimed += reclaimed;
> - *total_scanned += nr_scanned;
> spin_lock_irq(&mctz->lock);
> __mem_cgroup_remove_exceeded(mz, mctz);
>
> --
> 2.23.0
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2022-03-28 12:01 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-03-28 11:41 [PATCH] mm/memcg: remove unneeded nr_scanned Miaohe Lin
2022-03-28 12:01 ` Michal Hocko [this message]
2022-03-28 13:15 ` Miaohe Lin
2022-03-28 14:16 ` David Hildenbrand
2022-03-28 18:36 ` Roman Gushchin
2022-04-01 1:06 ` Wei Yang
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