Re: [PATCH v5 7/7] mm: memcontrol: make the slab calculation consistent
From: Shakeel Butt <hidden>
Date: 2020-12-23 21:22:49
Also in:
linux-fsdevel, linux-mm, lkml
On Wed, Dec 16, 2020 at 7:46 PM Muchun Song [off-list ref] 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;
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?
quoted hunk ↗ jump to hunk
Signed-off-by: Muchun Song <redacted> --- 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.
quoted hunk ↗ jump to hunk
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