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From: "Michal Koutný" <mkoutny@suse.com>
To: Johannes Weiner <hannes@cmpxchg.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Tejun Heo <tj@kernel.org>, Michal Hocko <mhocko@suse.com>,
	Roman Gushchin <guro@fb.com>, Shakeel Butt <shakeelb@google.com>,
	linux-mm@kvack.org, cgroups@vger.kernel.org,
	linux-kernel@vger.kernel.org, kernel-team@fb.com
Subject: Re: [PATCH v3 4/8] cgroup: rstat: support cgroup1
Date: Wed, 17 Feb 2021 18:42:32 +0100	[thread overview]
Message-ID: <20210217174232.GA19239@blackbody.suse.cz> (raw)
In-Reply-To: <20210209163304.77088-5-hannes@cmpxchg.org>

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Hello.

On Tue, Feb 09, 2021 at 11:33:00AM -0500, Johannes Weiner <hannes@cmpxchg.org> wrote:
> @@ -1971,10 +1978,14 @@ int cgroup_setup_root(struct cgroup_root *root, u16 ss_mask)
>  	if (ret)
>  		goto destroy_root;
>  
> -	ret = rebind_subsystems(root, ss_mask);
> +	ret = cgroup_rstat_init(root_cgrp);
Would it make sense to do cgroup_rstat_init() only if there's a subsys
in ss_mask that makes use of rstat?
(On legacy systems there could be individual hierarchy for each
controller so the rstat space can be saved.)

> @@ -5159,11 +5170,9 @@ static struct cgroup *cgroup_create(struct cgroup *parent, const char *name,
>  	if (ret)
>  		goto out_free_cgrp;
>  
> -	if (cgroup_on_dfl(parent)) {
> -		ret = cgroup_rstat_init(cgrp);
> -		if (ret)
> -			goto out_cancel_ref;
> -	}
> +	ret = cgroup_rstat_init(cgrp);
And here do cgroup_rstat_init() only when parent has it.

> @@ -285,8 +285,6 @@ void __init cgroup_rstat_boot(void)
>  
>  	for_each_possible_cpu(cpu)
>  		raw_spin_lock_init(per_cpu_ptr(&cgroup_rstat_cpu_lock, cpu));
> -
> -	BUG_ON(cgroup_rstat_init(&cgrp_dfl_root.cgrp));
>  }
Regardless of the suggestion above, this removal obsoletes the comment
cgroup_rstat_init:

         int cpu;
 
-        /* the root cgrp has rstat_cpu preallocated */
         if (!cgrp->rstat_cpu) {
                 cgrp->rstat_cpu = alloc_percpu(struct cgroup_rstat_cpu);

Regards,
Michal

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  reply	other threads:[~2021-02-17 17:42 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-02-09 16:32 [PATCH v3 0/8] mm: memcontrol: switch to rstat Johannes Weiner
2021-02-09 16:32 ` [PATCH v3 1/8] mm: memcontrol: fix cpuhotplug statistics flushing Johannes Weiner
2021-02-17 17:43   ` Michal Koutný
2021-02-09 16:32 ` [PATCH v3 2/8] mm: memcontrol: kill mem_cgroup_nodeinfo() Johannes Weiner
2021-02-17 17:43   ` Michal Koutný
2021-02-09 16:32 ` [PATCH v3 3/8] mm: memcontrol: privatize memcg_page_state query functions Johannes Weiner
2021-02-17 17:44   ` Michal Koutný
2021-02-09 16:33 ` [PATCH v3 4/8] cgroup: rstat: support cgroup1 Johannes Weiner
2021-02-17 17:42   ` Michal Koutný [this message]
2021-02-17 20:52     ` Johannes Weiner
2021-02-18 15:45       ` Michal Koutný
2021-02-18 17:06         ` Johannes Weiner
2021-02-09 16:33 ` [PATCH v3 5/8] cgroup: rstat: punt root-level optimization to individual controllers Johannes Weiner
2021-02-09 16:33 ` [PATCH v3 6/8] mm: memcontrol: switch to rstat Johannes Weiner
2021-02-18 15:36   ` Michal Koutný
2021-02-09 16:33 ` [PATCH v3 7/8] mm: memcontrol: consolidate lruvec stat flushing Johannes Weiner
2021-02-09 20:21   ` Roman Gushchin
2021-02-09 16:33 ` [PATCH v3 8/8] kselftests: cgroup: update kmem test for new vmstat implementation Johannes Weiner
2021-02-09 20:17   ` Roman Gushchin
2021-02-18 15:37   ` Michal Koutný

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