On Thu, Dec 3, 2020 at 5:16 AM Roman Gushchin <guro@xxxxxx> wrote:
>
> 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.
Agree. But here we cannot use BUILD_BUG_ON(). The compiler will
complain about it.
>
>
> > + 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.
Will do.
>
> > 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
> >
--
Yours,
Muchun
