Re: [PATCH v3 03/19] mm: memcg: convert vmstat slab counters to bytes

[Johannes Weiner]

On Wed, Apr 22, 2020 at 01:46:52PM -0700, 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@xxxxxx>

Acked-by: Johannes Weiner <hannes@xxxxxxxxxxx>

Thanks for splitting this out, it makes both this and the previous
patch easier to read.