From: Shakeel Butt <shakeelb@google.com>
To: Roman Gushchin <roman.gushchin@linux.dev>
Cc: linux-mm@kvack.org, cgroups@vger.kernel.org,
linux-kernel@vger.kernel.org,
Johannes Weiner <hannes@cmpxchg.org>,
Michal Hocko <mhocko@kernel.org>,
Muchun Song <muchun.song@linux.dev>,
Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH RFC 2/2] mm: kmem: add direct objcg pointer to task_struct
Date: Tue, 20 Dec 2022 20:44:51 +0000 [thread overview]
Message-ID: <20221220204451.gm5d3pdbfvd5ki6b@google.com> (raw)
In-Reply-To: <20221220182745.1903540-3-roman.gushchin@linux.dev>
On Tue, Dec 20, 2022 at 10:27:45AM -0800, Roman Gushchin wrote:
> To charge a freshly allocated kernel object to a memory cgroup, the
> kernel needs to obtain an objcg pointer. Currently it does it
> indirectly by obtaining the memcg pointer first and then calling to
> __get_obj_cgroup_from_memcg().
>
> Usually tasks spend their entire life belonging to the same object
> cgroup. So it makes sense to save the objcg pointer on task_struct
> directly, so it can be obtained faster. It requires some work on fork,
> exit and cgroup migrate paths, but these paths are way colder.
>
> The old indirect way is still used for remote memcg charging.
>
> Signed-off-by: Roman Gushchin <roman.gushchin@linux.dev>
This looks good too. Few comments below:
[...]
> +
> +#ifdef CONFIG_MEMCG_KMEM
> +static void mem_cgroup_kmem_attach(struct cgroup_taskset *tset)
> +{
> + struct task_struct *task;
> + struct cgroup_subsys_state *css;
> +
> + cgroup_taskset_for_each(task, css, tset) {
> + struct mem_cgroup *memcg;
> +
> + if (task->objcg)
> + obj_cgroup_put(task->objcg);
> +
> + rcu_read_lock();
> + memcg = container_of(css, struct mem_cgroup, css);
> + task->objcg = __get_obj_cgroup_from_memcg(memcg);
> + rcu_read_unlock();
> + }
> +}
> +#else
> +static void mem_cgroup_kmem_attach(struct cgroup_taskset *tset) {}
> +#endif /* CONFIG_MEMCG_KMEM */
> +
> +#if defined(CONFIG_MEMCG_KMEM) || defined(CONFIG_MEMCG_KMEM)
I think you want CONFIG_LRU_GEN in the above check.
> static void mem_cgroup_attach(struct cgroup_taskset *tset)
> {
> + mem_cgroup_lru_gen_attach(tset);
> + mem_cgroup_kmem_attach(tset);
> }
> -#endif /* CONFIG_LRU_GEN */
> +#endif
>
> static int seq_puts_memcg_tunable(struct seq_file *m, unsigned long value)
> {
> @@ -6816,9 +6872,15 @@ struct cgroup_subsys memory_cgrp_subsys = {
> .css_reset = mem_cgroup_css_reset,
> .css_rstat_flush = mem_cgroup_css_rstat_flush,
> .can_attach = mem_cgroup_can_attach,
> +#if defined(CONFIG_MEMCG_KMEM) || defined(CONFIG_MEMCG_KMEM)
Same here.
> .attach = mem_cgroup_attach,
> +#endif
> .cancel_attach = mem_cgroup_cancel_attach,
> .post_attach = mem_cgroup_move_task,
> +#ifdef CONFIG_MEMCG_KMEM
> + .fork = mem_cgroup_fork,
> + .exit = mem_cgroup_exit,
> +#endif
> .dfl_cftypes = memory_files,
> .legacy_cftypes = mem_cgroup_legacy_files,
> .early_init = 0,
> --
> 2.39.0
>
next prev parent reply other threads:[~2022-12-20 20:44 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-12-20 18:27 [PATCH RFC 0/2] mm: kmem: optimize obj_cgroup pointer retrieval Roman Gushchin
2022-12-20 18:27 ` [PATCH RFC 1/2] mm: kmem: optimize get_obj_cgroup_from_current() Roman Gushchin
2022-12-20 19:55 ` Shakeel Butt
2022-12-20 21:15 ` Roman Gushchin
2022-12-20 18:27 ` [PATCH RFC 2/2] mm: kmem: add direct objcg pointer to task_struct Roman Gushchin
2022-12-20 20:44 ` Shakeel Butt [this message]
2022-12-22 13:50 ` Michal Koutný
2022-12-22 16:21 ` Roman Gushchin
2023-01-02 16:09 ` Michal Koutný
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