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From: Muchun Song <songmuchun@bytedance.com>
To: "Michal Koutný" <mkoutny@suse.com>,
	"Mika Penttilä" <mika.penttila@nextfour.com>
Cc: Matthew Wilcox <willy@infradead.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Michal Hocko <mhocko@kernel.org>,
	Vladimir Davydov <vdavydov.dev@gmail.com>,
	Shakeel Butt <shakeelb@google.com>, Roman Gushchin <guro@fb.com>,
	Yang Shi <shy828301@gmail.com>, Alex Shi <alexs@kernel.org>,
	Wei Yang <richard.weiyang@gmail.com>,
	Dave Chinner <david@fromorbit.com>,
	trond.myklebust@hammerspace.com, anna.schumaker@netapp.com,
	jaegeuk@kernel.org, chao@kernel.org,
	Kari Argillander <kari.argillander@gmail.com>,
	linux-fsdevel <linux-fsdevel@vger.kernel.org>,
	LKML <linux-kernel@vger.kernel.org>,
	Linux Memory Management List <linux-mm@kvack.org>,
	linux-nfs@vger.kernel.org, Qi Zheng <zhengqi.arch@bytedance.com>,
	Xiongchun duan <duanxiongchun@bytedance.com>,
	Fam Zheng <fam.zheng@bytedance.com>,
	Muchun Song <smuchun@gmail.com>
Subject: Re: [PATCH v5 13/16] mm: memcontrol: reuse memory cgroup ID for kmem ID
Date: Thu, 6 Jan 2022 11:34:58 +0800	[thread overview]
Message-ID: <CAMZfGtWhYOFCKtFoHB7vsKmpEdj9F-axkba6p9EpuPUp3BK-ag@mail.gmail.com> (raw)
In-Reply-To: <20220105170348.GA21070@blackbody.suse.cz>

On Thu, Jan 6, 2022 at 1:03 AM Michal Koutný <mkoutny@suse.com> wrote:
>
> On Mon, Dec 20, 2021 at 04:56:46PM +0800, Muchun Song <songmuchun@bytedance.com> wrote:
> > There are two idrs being used by memory cgroup, one is for kmem ID,
> > another is for memory cgroup ID. The maximum ID of both is 64Ki.
> > Both of them can limit the total number of memory cgroups.
> > Actually, we can reuse memory cgroup ID for kmem ID to simplify the
> > code.
>
> An interesting improvement.
>
> I'm a bit dense -- what's the purpose the MEM_CGROUP_ID_DIFF offset?

Hi Michal and Mika,

MEM_CGROUP_ID_DIFF is introduced to be consistent with before
that kmem ID starts with -1 and has no holes. Actually, it can be dropped
and make memcg->kmemcg_id equal to memcg->id.id directly.

> Couldn't this deduplication be extended to only use mem_cgroup.id.id
> instead of mem_cgroup.kmemcg_id? (With a boolean telling whether kmem
> accounting is active.)
>

Not easy to completely remove memcg->kmemcg_id since this filed
will be used to sync list_lru reparenting which will change
memcg->kmemcg_id to its parent's kmem ID (more details refers to
memcg_drain_all_list_lrus() in patch 10 of this series).

Thanks.

  reply	other threads:[~2022-01-06  3:35 UTC|newest]

Thread overview: 45+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-12-20  8:56 [PATCH v5 00/16] Optimize list lru memory consumption Muchun Song
2021-12-20  8:56 ` [PATCH v5 01/16] mm: list_lru: optimize memory consumption of arrays of per cgroup lists Muchun Song
2022-01-07  0:05   ` Roman Gushchin
2022-01-09  4:49     ` Muchun Song
2022-01-10 18:42       ` Roman Gushchin
2022-01-11  3:19         ` Muchun Song
2021-12-20  8:56 ` [PATCH v5 02/16] mm: introduce kmem_cache_alloc_lru Muchun Song
2022-01-07  3:04   ` Roman Gushchin
2022-01-09  6:21     ` Muchun Song
2022-01-10 18:47       ` Roman Gushchin
2022-01-11 15:41         ` Vlastimil Babka
2022-01-11 17:54           ` Roman Gushchin
2021-12-20  8:56 ` [PATCH v5 03/16] fs: introduce alloc_inode_sb() to allocate filesystems specific inode Muchun Song
2022-01-11 18:55   ` Roman Gushchin
2022-01-12  2:54     ` Muchun Song
2021-12-20  8:56 ` [PATCH v5 04/16] fs: allocate inode by using alloc_inode_sb() Muchun Song
2022-01-11 18:58   ` Roman Gushchin
2022-01-12  2:55     ` Muchun Song
2021-12-20  8:56 ` [PATCH v5 05/16] f2fs: " Muchun Song
2022-01-11 19:03   ` Roman Gushchin
2021-12-20  8:56 ` [PATCH v5 06/16] nfs42: use a specific kmem_cache to allocate nfs4_xattr_entry Muchun Song
2021-12-20  8:56 ` [PATCH v5 07/16] mm: dcache: use kmem_cache_alloc_lru() to allocate dentry Muchun Song
2022-01-11 19:05   ` Roman Gushchin
2021-12-20  8:56 ` [PATCH v5 08/16] xarray: use kmem_cache_alloc_lru to allocate xa_node Muchun Song
2022-01-11 19:14   ` Roman Gushchin
2021-12-20  8:56 ` [PATCH v5 09/16] mm: memcontrol: move memcg_online_kmem() to mem_cgroup_css_online() Muchun Song
2022-01-11 19:17   ` Roman Gushchin
2021-12-20  8:56 ` [PATCH v5 10/16] mm: list_lru: allocate list_lru_one only when needed Muchun Song
2022-01-06 11:00   ` Michal Koutný
2022-01-12 13:22     ` Muchun Song
2022-01-13 13:32       ` Michal Koutný
2022-01-18 12:05         ` Muchun Song
2022-01-19  9:33           ` Michal Koutný
2022-01-21  5:28             ` Muchun Song
2022-01-11 20:00   ` Roman Gushchin
2022-01-12  4:48     ` Muchun Song
2021-12-20  8:56 ` [PATCH v5 11/16] mm: list_lru: rename memcg_drain_all_list_lrus to memcg_reparent_list_lrus Muchun Song
2021-12-20  8:56 ` [PATCH v5 12/16] mm: list_lru: replace linear array with xarray Muchun Song
2021-12-20  8:56 ` [PATCH v5 13/16] mm: memcontrol: reuse memory cgroup ID for kmem ID Muchun Song
2021-12-20  9:27   ` Mika Penttilä
2022-01-05 17:03   ` Michal Koutný
2022-01-06  3:34     ` Muchun Song [this message]
2021-12-20  8:56 ` [PATCH v5 14/16] mm: memcontrol: fix cannot alloc the maximum memcg ID Muchun Song
2021-12-20  8:56 ` [PATCH v5 15/16] mm: list_lru: rename list_lru_per_memcg to list_lru_memcg Muchun Song
2021-12-20  8:56 ` [PATCH v5 16/16] mm: memcontrol: rename memcg_cache_id to memcg_kmem_id Muchun Song

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