Re: [External] Re: [PATCH v3 7/7] mm: memcontrol: make the slab calculation consistent

From: Muchun Song
Date: Tue Dec 15 2020 - 11:23:35 EST

On Tue, Dec 15, 2020 at 9:35 PM Michal Hocko <mhocko@xxxxxxxx> wrote:
>
> On Tue 08-12-20 12:18:47, 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.
> >
> > We can drop the ratio in struct memory_stat. This can make the code
> > clean and simple. And get rid of the awkward mix of static and runtime
> > initialization of the memory_stats table.
>
> This changelog doesn't explain, what is the problem, why do we care and
> why the additional code is worthwile.

Thank you. Will update the commit log for more clear.

>
> > Signed-off-by: Muchun Song <songmuchun@xxxxxxxxxxxxx>
> > ---
> > mm/memcontrol.c | 112 ++++++++++++++++++++++++++++++++++++--------------------
> > 1 file changed, 73 insertions(+), 39 deletions(-)
> >
> > diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> > index a40797a27f87..841ea37cc123 100644
> > --- a/mm/memcontrol.c
> > +++ b/mm/memcontrol.c
> > @@ -1511,49 +1511,78 @@ static bool mem_cgroup_wait_acct_move(struct mem_cgroup *memcg)
> >
> > struct memory_stat {
> > const char *name;
> > - unsigned int ratio;
> > unsigned int idx;
> > };
> >
> > static const struct memory_stat memory_stats[] = {
> > - { "anon", PAGE_SIZE, NR_ANON_MAPPED },
> > - { "file", PAGE_SIZE, NR_FILE_PAGES },
> > - { "kernel_stack", 1024, NR_KERNEL_STACK_KB },
> > - { "pagetables", PAGE_SIZE, NR_PAGETABLE },
> > - { "percpu", 1, MEMCG_PERCPU_B },
> > - { "sock", PAGE_SIZE, MEMCG_SOCK },
> > - { "shmem", PAGE_SIZE, NR_SHMEM },
> > - { "file_mapped", PAGE_SIZE, NR_FILE_MAPPED },
> > - { "file_dirty", PAGE_SIZE, NR_FILE_DIRTY },
> > - { "file_writeback", PAGE_SIZE, NR_WRITEBACK },
> > + { "anon", NR_ANON_MAPPED },
> > + { "file", NR_FILE_PAGES },
> > + { "kernel_stack", NR_KERNEL_STACK_KB },
> > + { "pagetables", NR_PAGETABLE },
> > + { "percpu", MEMCG_PERCPU_B },
> > + { "sock", MEMCG_SOCK },
> > + { "shmem", NR_SHMEM },
> > + { "file_mapped", NR_FILE_MAPPED },
> > + { "file_dirty", NR_FILE_DIRTY },
> > + { "file_writeback", NR_WRITEBACK },
> > #ifdef CONFIG_TRANSPARENT_HUGEPAGE
> > - { "anon_thp", PAGE_SIZE, NR_ANON_THPS },
> > - { "file_thp", PAGE_SIZE, NR_FILE_THPS },
> > - { "shmem_thp", PAGE_SIZE, NR_SHMEM_THPS },
> > + { "anon_thp", NR_ANON_THPS },
> > + { "file_thp", NR_FILE_THPS },
> > + { "shmem_thp", NR_SHMEM_THPS },
> > #endif
> > - { "inactive_anon", PAGE_SIZE, NR_INACTIVE_ANON },
> > - { "active_anon", PAGE_SIZE, NR_ACTIVE_ANON },
> > - { "inactive_file", PAGE_SIZE, NR_INACTIVE_FILE },
> > - { "active_file", PAGE_SIZE, NR_ACTIVE_FILE },
> > - { "unevictable", PAGE_SIZE, NR_UNEVICTABLE },
> > -
> > - /*
> > - * Note: The slab_reclaimable and slab_unreclaimable must be
> > - * together and slab_reclaimable must be in front.
> > - */
> > - { "slab_reclaimable", 1, NR_SLAB_RECLAIMABLE_B },
> > - { "slab_unreclaimable", 1, NR_SLAB_UNRECLAIMABLE_B },
> > + { "inactive_anon", NR_INACTIVE_ANON },
> > + { "active_anon", NR_ACTIVE_ANON },
> > + { "inactive_file", NR_INACTIVE_FILE },
> > + { "active_file", NR_ACTIVE_FILE },
> > + { "unevictable", NR_UNEVICTABLE },
> > + { "slab_reclaimable", NR_SLAB_RECLAIMABLE_B },
> > + { "slab_unreclaimable", NR_SLAB_UNRECLAIMABLE_B },
> >
> > /* The memory events */
> > - { "workingset_refault_anon", 1, WORKINGSET_REFAULT_ANON },
> > - { "workingset_refault_file", 1, WORKINGSET_REFAULT_FILE },
> > - { "workingset_activate_anon", 1, WORKINGSET_ACTIVATE_ANON },
> > - { "workingset_activate_file", 1, WORKINGSET_ACTIVATE_FILE },
> > - { "workingset_restore_anon", 1, WORKINGSET_RESTORE_ANON },
> > - { "workingset_restore_file", 1, WORKINGSET_RESTORE_FILE },
> > - { "workingset_nodereclaim", 1, WORKINGSET_NODERECLAIM },
> > + { "workingset_refault_anon", WORKINGSET_REFAULT_ANON },
> > + { "workingset_refault_file", WORKINGSET_REFAULT_FILE },
> > + { "workingset_activate_anon", WORKINGSET_ACTIVATE_ANON },
> > + { "workingset_activate_file", WORKINGSET_ACTIVATE_FILE },
> > + { "workingset_restore_anon", WORKINGSET_RESTORE_ANON },
> > + { "workingset_restore_file", WORKINGSET_RESTORE_FILE },
> > + { "workingset_nodereclaim", WORKINGSET_NODERECLAIM },
> > };
> >
> > +/* Translate stat items to the correct unit for memory.stat output */
> > +static int memcg_page_state_unit(int item)
> > +{
> > + int unit;
> > +
> > + switch (item) {
> > + case MEMCG_PERCPU_B:
> > + case NR_SLAB_RECLAIMABLE_B:
> > + case NR_SLAB_UNRECLAIMABLE_B:
> > + case WORKINGSET_REFAULT_ANON:
> > + case WORKINGSET_REFAULT_FILE:
> > + case WORKINGSET_ACTIVATE_ANON:
> > + case WORKINGSET_ACTIVATE_FILE:
> > + case WORKINGSET_RESTORE_ANON:
> > + case WORKINGSET_RESTORE_FILE:
> > + case WORKINGSET_NODERECLAIM:
> > + unit = 1;
> > + break;
> > + case NR_KERNEL_STACK_KB:
> > + unit = SZ_1K;
> > + break;
> > + default:
> > + unit = PAGE_SIZE;
> > + break;
> > + }
> > +
> > + return unit;
> > +}
> > +
> > +static inline unsigned long memcg_page_state_output(struct mem_cgroup *memcg,
> > + int item)
> > +{
> > + return memcg_page_state(memcg, item) * memcg_page_state_unit(item);
> > +}
> > +
> > static char *memory_stat_format(struct mem_cgroup *memcg)
> > {
> > struct seq_buf s;
> > @@ -1577,13 +1606,12 @@ static char *memory_stat_format(struct mem_cgroup *memcg)
> > for (i = 0; i < ARRAY_SIZE(memory_stats); i++) {
> > u64 size;
> >
> > - size = memcg_page_state(memcg, memory_stats[i].idx);
> > - size *= memory_stats[i].ratio;
> > + size = memcg_page_state_output(memcg, memory_stats[i].idx);
> > seq_buf_printf(&s, "%s %llu\n", memory_stats[i].name, size);
> >
> > 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);
> > + size += memcg_page_state_output(memcg,
> > + NR_SLAB_RECLAIMABLE_B);
> > seq_buf_printf(&s, "slab %llu\n", size);
> > }
> > }
> > @@ -6377,6 +6405,12 @@ static int memory_stat_show(struct seq_file *m, void *v)
> > }
> >
> > #ifdef CONFIG_NUMA
> > +static inline unsigned long lruvec_page_state_output(struct lruvec *lruvec,
> > + int item)
> > +{
> > + return lruvec_page_state(lruvec, item) * memcg_page_state_unit(item);
> > +}
> > +
> > static int memory_numa_stat_show(struct seq_file *m, void *v)
> > {
> > int i;
> > @@ -6394,8 +6428,8 @@ static int memory_numa_stat_show(struct seq_file *m, void *v)
> > struct lruvec *lruvec;
> >
> > lruvec = mem_cgroup_lruvec(memcg, NODE_DATA(nid));
> > - size = lruvec_page_state(lruvec, memory_stats[i].idx);
> > - size *= memory_stats[i].ratio;
> > + size = lruvec_page_state_output(lruvec,
> > + memory_stats[i].idx);
> > seq_printf(m, " N%d=%llu", nid, size);
> > }
> > seq_putc(m, '\n');
> > --
> > 2.11.0
>
> --
> Michal Hocko
> SUSE Labs



--
Yours,
Muchun