On Wed, Dec 02, 2020 at 08:14:34PM +0800, Muchun Song wrote:
> Although the ratio of the slab is one, we also should read the ratio
> from the related memory_stats instead of hard-coding. And the local
> variable of size is already the value of slab_unreclaimable. So we
> do not need to read again. Simplify the code here.
>
> Signed-off-by: Muchun Song <songmuchun@xxxxxxxxxxxxx>
> ---
> mm/memcontrol.c | 22 +++++++++++++++++-----
> 1 file changed, 17 insertions(+), 5 deletions(-)
Hi Muchun!
>
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index 9922f1510956..03a9c64560f6 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -1545,12 +1545,22 @@ static int __init memory_stats_init(void)
> int i;
>
> for (i = 0; i < ARRAY_SIZE(memory_stats); i++) {
> + switch (memory_stats[i].idx) {
> #ifdef CONFIG_TRANSPARENT_HUGEPAGE
> - if (memory_stats[i].idx == NR_ANON_THPS ||
> - memory_stats[i].idx == NR_FILE_THPS ||
> - memory_stats[i].idx == NR_SHMEM_THPS)
> + case NR_ANON_THPS:
> + case NR_FILE_THPS:
> + case NR_SHMEM_THPS:
> memory_stats[i].ratio = HPAGE_PMD_SIZE;
> + break;
> #endif
> + case NR_SLAB_UNRECLAIMABLE_B:
> + VM_BUG_ON(i < 1);
> + VM_BUG_ON(memory_stats[i - 1].idx != NR_SLAB_RECLAIMABLE_B);
Please, convert these to BUILD_BUG_ON(), they don't have to be runtime checks.
> + break;
> + default:
> + break;
> + }
> +
> VM_BUG_ON(!memory_stats[i].ratio);
> VM_BUG_ON(memory_stats[i].idx >= MEMCG_NR_STAT);
> }
> @@ -1587,8 +1597,10 @@ static char *memory_stat_format(struct mem_cgroup *memcg)
> seq_buf_printf(&s, "%s %llu\n", memory_stats[i].name, size);
>
Can you, please, add a small comment here stating that we're printing
unreclaimable, reclaimable and the sum of both? It will simplify the reading of the code.
> if (unlikely(memory_stats[i].idx == NR_SLAB_UNRECLAIMABLE_B)) {
> - size = memcg_page_state(memcg, NR_SLAB_RECLAIMABLE_B) +
> - memcg_page_state(memcg, NR_SLAB_UNRECLAIMABLE_B);
> + int idx = i - 1;
> +
> + size += memcg_page_state(memcg, memory_stats[idx].idx) *
> + memory_stats[idx].ratio;
> seq_buf_printf(&s, "slab %llu\n", size);
> }
> }
Otherwise the patch looks good to me! Please, feel free to add
Acked-by: Roman Gushchin <guro@xxxxxx>
after addressing my comments.
Thanks!
> --
> 2.11.0
>
