From: Johannes Weiner <hannes-druUgvl0LCNAfugRpC6u6w@public.gmane.org>
To: Chris Down <chris-6Bi1550iOqEnzZ6mRAm98g@public.gmane.org>
Cc: Andrew Morton
<akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>,
Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>,
linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org,
cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
kernel-team-b10kYP2dOMg@public.gmane.org
Subject: Re: [PATCH] mm, memcg: Bypass high reclaim iteration for cgroup hierarchy root
Date: Thu, 2 Apr 2020 11:18:52 -0400 [thread overview]
Message-ID: <20200402151852.GD2089@cmpxchg.org> (raw)
In-Reply-To: <20200312164137.GA1753625-6Bi1550iOqEnzZ6mRAm98g@public.gmane.org>
On Thu, Mar 12, 2020 at 04:41:37PM +0000, Chris Down wrote:
> The root of the hierarchy cannot have high set, so we will never reclaim
> based on it. This makes that clearer and avoids another entry.
>
> Signed-off-by: Chris Down <chris-6Bi1550iOqEnzZ6mRAm98g@public.gmane.org>
> Cc: Andrew Morton <akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>
> Cc: Johannes Weiner <hannes-druUgvl0LCNAfugRpC6u6w@public.gmane.org>
> Cc: Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
> Cc: linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org
> Cc: cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
> Cc: linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
> Cc: kernel-team-b10kYP2dOMg@public.gmane.org
This makes sense, memory.high doesn't exist on the root.
And the mem_cgroup_is_root() check, a simple pointer comparison, is
cheaper than reading the page_counter atomic and memcg->high (which we
already know to be PAGE_COUNTER_MAX).
Acked-by: Johannes Weiner <hannes-druUgvl0LCNAfugRpC6u6w@public.gmane.org>
WARNING: multiple messages have this Message-ID (diff)
From: Johannes Weiner <hannes@cmpxchg.org>
To: Chris Down <chris@chrisdown.name>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Tejun Heo <tj@kernel.org>,
linux-mm@kvack.org, cgroups@vger.kernel.org,
linux-kernel@vger.kernel.org, kernel-team@fb.com
Subject: Re: [PATCH] mm, memcg: Bypass high reclaim iteration for cgroup hierarchy root
Date: Thu, 2 Apr 2020 11:18:52 -0400 [thread overview]
Message-ID: <20200402151852.GD2089@cmpxchg.org> (raw)
In-Reply-To: <20200312164137.GA1753625@chrisdown.name>
On Thu, Mar 12, 2020 at 04:41:37PM +0000, Chris Down wrote:
> The root of the hierarchy cannot have high set, so we will never reclaim
> based on it. This makes that clearer and avoids another entry.
>
> Signed-off-by: Chris Down <chris@chrisdown.name>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Johannes Weiner <hannes@cmpxchg.org>
> Cc: Tejun Heo <tj@kernel.org>
> Cc: linux-mm@kvack.org
> Cc: cgroups@vger.kernel.org
> Cc: linux-kernel@vger.kernel.org
> Cc: kernel-team@fb.com
This makes sense, memory.high doesn't exist on the root.
And the mem_cgroup_is_root() check, a simple pointer comparison, is
cheaper than reading the page_counter atomic and memcg->high (which we
already know to be PAGE_COUNTER_MAX).
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
next prev parent reply other threads:[~2020-04-02 15:18 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-12 16:41 [PATCH] mm, memcg: Bypass high reclaim iteration for cgroup hierarchy root Chris Down
2020-03-12 16:41 ` Chris Down
[not found] ` <20200312164137.GA1753625-6Bi1550iOqEnzZ6mRAm98g@public.gmane.org>
2020-04-02 1:23 ` Andrew Morton
2020-04-02 1:23 ` Andrew Morton
2020-04-02 15:18 ` Johannes Weiner [this message]
2020-04-02 15:18 ` Johannes Weiner
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