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Subject: Re: [PATCH v2] proc: add percpu populated pages count to meminfo
To:     Dennis Zhou <dennisszhou@gmail.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Tejun Heo <tj@kernel.org>,
        Johannes Weiner <hannes@cmpxchg.org>,
        Christoph Lameter <cl@linux.com>, Roman Gushchin <guro@fb.com>
Cc:     kernel-team@fb.com, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org, Linux API <linux-api@vger.kernel.org>
References: <20180807184723.74919-1-dennisszhou@gmail.com>
From:   Vlastimil Babka <vbabka@suse.cz>
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Message-ID: <4eb4a0cc-2304-b6e2-06dd-ce0ade5d537e@suse.cz>
Date:   Wed, 8 Aug 2018 09:53:32 +0200
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On 08/07/2018 08:47 PM, Dennis Zhou wrote:
> From: "Dennis Zhou (Facebook)" <dennisszhou@gmail.com>
> 
> Currently, percpu memory only exposes allocation and utilization
> information via debugfs. This more or less is only really useful for
> understanding the fragmentation and allocation information at a
> per-chunk level with a few global counters. This is also gated behind a
> config. BPF and cgroup, for example, have seen an increase use causing
> increased use of percpu memory. Let's make it easier for someone to
> identify how much memory is being used.
> 
> This patch adds the "Percpu" stat to meminfo to more easily look up how
> much percpu memory is in use. This number includes the cost for all
> allocated backing pages and not just isnight at the a unit, per chunk
> level. Metadata is excluded. I think excluding metadata is fair because
> the backing memory scales with the numbere of cpus and can quickly
> outweigh the metadata. It also makes this calculation light.
> 
> Signed-off-by: Dennis Zhou <dennisszhou@gmail.com>

Acked-by: Vlastimil Babka <vbabka@suse.cz>

Thanks.