On Fri, Apr 26, 2024 at 5:37 PM Shakeel Butt <shakeel.butt@xxxxxxxxx> wrote:
>
> At the moment, the amount of memory allocated for stats related structs
> in the mem_cgroup corresponds to the size of enum node_stat_item.
> However not all fields in enum node_stat_item has corresponding memcg
> stats. So, let's use indirection mechanism similar to the one used for
> memcg vmstats management.
>
> For a given x86_64 config, the size of stats with and without patch is:
>
> structs size in bytes w/o with
>
> struct lruvec_stats 1128 648
> struct lruvec_stats_percpu 752 432
> struct memcg_vmstats 1832 1352
> struct memcg_vmstats_percpu 1280 960
>
> The memory savings is further compounded by the fact that these structs
> are allocated for each cpu and for each node. To be precise, for each
> memcg the memory saved would be:
>
> Memory saved = ((21 * 3 * NR_NODES) + (21 * 2 * NR_NODS * NR_CPUS) +
> (21 * 3) + (21 * 2 * NR_CPUS)) * sizeof(long)
>
> Where 21 is the number of fields eliminated.
>
> Signed-off-by: Shakeel Butt <shakeel.butt@xxxxxxxxx>
> ---
> mm/memcontrol.c | 138 ++++++++++++++++++++++++++++++++++++++++--------
> 1 file changed, 115 insertions(+), 23 deletions(-)
>
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index 5e337ed6c6bf..c164bc9b8ed6 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -576,35 +576,105 @@ mem_cgroup_largest_soft_limit_node(struct mem_cgroup_tree_per_node *mctz)
> return mz;
> }
>
> +/* Subset of node_stat_item for memcg stats */
> +static const unsigned int memcg_node_stat_items[] = {
> + NR_INACTIVE_ANON,
> + NR_ACTIVE_ANON,
> + NR_INACTIVE_FILE,
> + NR_ACTIVE_FILE,
> + NR_UNEVICTABLE,
> + NR_SLAB_RECLAIMABLE_B,
> + NR_SLAB_UNRECLAIMABLE_B,
> + WORKINGSET_REFAULT_ANON,
> + WORKINGSET_REFAULT_FILE,
> + WORKINGSET_ACTIVATE_ANON,
> + WORKINGSET_ACTIVATE_FILE,
> + WORKINGSET_RESTORE_ANON,
> + WORKINGSET_RESTORE_FILE,
> + WORKINGSET_NODERECLAIM,
> + NR_ANON_MAPPED,
> + NR_FILE_MAPPED,
> + NR_FILE_PAGES,
> + NR_FILE_DIRTY,
> + NR_WRITEBACK,
> + NR_SHMEM,
> + NR_SHMEM_THPS,
> + NR_FILE_THPS,
> + NR_ANON_THPS,
> + NR_KERNEL_STACK_KB,
> + NR_PAGETABLE,
> + NR_SECONDARY_PAGETABLE,
> +#ifdef CONFIG_SWAP
> + NR_SWAPCACHE,
> +#endif
> +};
> +
> +static const unsigned int memcg_stat_items[] = {
> + MEMCG_SWAP,
> + MEMCG_SOCK,
> + MEMCG_PERCPU_B,
> + MEMCG_VMALLOC,
> + MEMCG_KMEM,
> + MEMCG_ZSWAP_B,
> + MEMCG_ZSWAPPED,
> +};
Unsigned for these? All the values are positive now, but I don't think
we'll get a build warning if a negative one ever got added, just a
crash or corruption. BUG_ON in init_memcg_stats if a
memcg_stat_items[i] < 0?
