linux-kernel - Re: [PATCH v4 03/19] mm: memcg: convert vmstat slab counters to bytes

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Message-ID: <a0a6c013-3a08-86f5-46a4-808a8c63a50a@suse.cz>
Date:   Wed, 27 May 2020 13:43:16 +0200
From:   Vlastimil Babka <vbabka@...e.cz>
To:     Roman Gushchin <guro@...com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Christoph Lameter <cl@...ux.com>
Cc:     Johannes Weiner <hannes@...xchg.org>,
        Michal Hocko <mhocko@...nel.org>,
        Shakeel Butt <shakeelb@...gle.com>, linux-mm@...ck.org,
        kernel-team@...com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 03/19] mm: memcg: convert vmstat slab counters to bytes

On 5/26/20 11:42 PM, Roman Gushchin wrote:
> In order to prepare for per-object slab memory accounting, convert
> NR_SLAB_RECLAIMABLE and NR_SLAB_UNRECLAIMABLE vmstat items to bytes.
> 
> To make it obvious, rename them to NR_SLAB_RECLAIMABLE_B and
> NR_SLAB_UNRECLAIMABLE_B (similar to NR_KERNEL_STACK_KB).
> 
> Internally global and per-node counters are stored in pages,
> however memcg and lruvec counters are stored in bytes.
> This scheme may look weird, but only for now. As soon as slab
> pages will be shared between multiple cgroups, global and
> node counters will reflect the total number of slab pages.
> However memcg and lruvec counters will be used for per-memcg
> slab memory tracking, which will take separate kernel objects
> in the account. Keeping global and node counters in pages helps
> to avoid additional overhead.
> 
> The size of slab memory shouldn't exceed 4Gb on 32-bit machines,
> so it will fit into atomic_long_t we use for vmstats.
> 
> Signed-off-by: Roman Gushchin <guro@...com>

You didn't add Acked-by: Johannes Weiner <hannes@...xchg.org>
( see 20200507204137.GC161043@...xchg.org )
(Noticed thanks to the great 'b4 am' and 'git range-diff' tools)

Reviewed-by: Vlastimil Babka <vbabka@...e.cz>