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Message-ID: <CAMZfGtXE7jcGKugDKXb7k9Ly0vmoba22sp=QpNeCR-sNMv=wQg@mail.gmail.com>
Date: Thu, 24 Dec 2020 10:43:53 +0800
From: Muchun Song <songmuchun@...edance.com>
To: Shakeel Butt <shakeelb@...gle.com>
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
"Rafael J. Wysocki" <rafael@...nel.org>,
Alexey Dobriyan <adobriyan@...il.com>,
Andrew Morton <akpm@...ux-foundation.org>,
Johannes Weiner <hannes@...xchg.org>,
Michal Hocko <mhocko@...nel.org>,
Vladimir Davydov <vdavydov.dev@...il.com>,
Hugh Dickins <hughd@...gle.com>, Roman Gushchin <guro@...com>,
Sami Tolvanen <samitolvanen@...gle.com>,
Feng Tang <feng.tang@...el.com>, Neil Brown <neilb@...e.de>,
Joonsoo Kim <iamjoonsoo.kim@....com>,
Randy Dunlap <rdunlap@...radead.org>,
LKML <linux-kernel@...r.kernel.org>,
linux-fsdevel <linux-fsdevel@...r.kernel.org>,
Linux MM <linux-mm@...ck.org>,
Cgroups <cgroups@...r.kernel.org>
Subject: Re: [External] Re: [PATCH v5 7/7] mm: memcontrol: make the slab
calculation consistent
On Thu, Dec 24, 2020 at 5:21 AM Shakeel Butt <shakeelb@...gle.com> wrote:
>
> On Wed, Dec 16, 2020 at 7:46 PM Muchun Song <songmuchun@...edance.com> 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.
> >
> > To do this we need some code like below:
> >
> > 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(memcg, memory_stats[i - 1].idx) *
> > + memory_stats[i - 1].ratio;
Hi Shakeel,
Here is the [i - 1].
> >
> > It requires a series of BUG_ONs or comments to ensure these two
> > items are actually adjacent and in the right order. So it would
> > probably be easier to implement this using a wrapper that has a
> > big switch() for unit conversion.
> >
> > This would fix the ratio inconsistency and get rid of the order
> > guarantee.
> >
>
> The commit message is really confusing. It is explaining a situation
> which it did not do. I don't see any benefit of mentioning BUG_ONs or
> [i-1]s in the message. The patch makes sure that we use the right
> ratio for slab. Can you rewrite the commit message and motivate in
> just that regard?
Yeah, I need rewrite the commit message to make it more clear.
However, here is a discussion about this. See
https://lore.kernel.org/patchwork/patch/1348611/
Thanks.
>
> > Signed-off-by: Muchun Song <songmuchun@...edance.com>
> > ---
> > mm/memcontrol.c | 105 +++++++++++++++++++++++++++++++++++---------------------
> > 1 file changed, 66 insertions(+), 39 deletions(-)
> >
> > diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> > index a40797a27f87..eec44918d373 100644
> > --- a/mm/memcontrol.c
> > +++ b/mm/memcontrol.c
> > @@ -1511,49 +1511,71 @@ 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)
> > +{
> > + 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:
> > + return 1;
> > + case NR_KERNEL_STACK_KB:
> > + return SZ_1K;
> > + default:
> > + return PAGE_SIZE;
> > + }
> > +}
> > +
> > +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 +1599,12 @@ 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 +6398,12 @@ 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);
> > +}
> > +
>
> No need to have lruvec_page_state_output() separately as there is just
> one user. Just inline it.
>
> > static int memory_numa_stat_show(struct seq_file *m, void *v)
> > {
> > int i;
> > @@ -6394,8 +6421,8 @@ 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
> >
--
Yours,
Muchun
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