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We reduce the count whenever an mTHP is completely unmapped. Signed-off-by: Barry Song --- Documentation/admin-guide/mm/transhuge.rst | 5 +++++ include/linux/huge_mm.h | 15 +++++++++++++-- mm/huge_memory.c | 2 ++ mm/rmap.c | 3 +++ 4 files changed, 23 insertions(+), 2 deletions(-) diff --git a/Documentation/admin-guide/mm/transhuge.rst b/Documentation/admin-guide/mm/transhuge.rst index 058485daf186..715f181543f6 100644 --- a/Documentation/admin-guide/mm/transhuge.rst +++ b/Documentation/admin-guide/mm/transhuge.rst @@ -527,6 +527,11 @@ split_deferred it would free up some memory. Pages on split queue are going to be split under memory pressure, if splitting is possible. +anon_num + the number of anon huge pages we have in the whole system. + These huge pages could be still entirely mapped and have partially + unmapped and unused subpages. + As the system ages, allocating huge pages may be expensive as the system uses memory compaction to copy data around memory to free a huge page for use. There are some counters in ``/proc/vmstat`` to help diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h index e25d9ebfdf89..294c348fe3cc 100644 --- a/include/linux/huge_mm.h +++ b/include/linux/huge_mm.h @@ -281,6 +281,7 @@ enum mthp_stat_item { MTHP_STAT_SPLIT, MTHP_STAT_SPLIT_FAILED, MTHP_STAT_SPLIT_DEFERRED, + MTHP_STAT_NR_ANON, __MTHP_STAT_COUNT }; @@ -291,14 +292,24 @@ struct mthp_stat { #ifdef CONFIG_SYSFS DECLARE_PER_CPU(struct mthp_stat, mthp_stats); -static inline void count_mthp_stat(int order, enum mthp_stat_item item) +static inline void mod_mthp_stat(int order, enum mthp_stat_item item, int delta) { if (order <= 0 || order > PMD_ORDER) return; - this_cpu_inc(mthp_stats.stats[order][item]); + this_cpu_add(mthp_stats.stats[order][item], delta); +} + +static inline void count_mthp_stat(int order, enum mthp_stat_item item) +{ + mod_mthp_stat(order, item, 1); } + #else +static inline void mod_mthp_stat(int order, enum mthp_stat_item item, int delta) +{ +} + static inline void count_mthp_stat(int order, enum mthp_stat_item item) { } diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 697fcf89f975..b6bc2a3791e3 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -578,6 +578,7 @@ DEFINE_MTHP_STAT_ATTR(shmem_fallback_charge, MTHP_STAT_SHMEM_FALLBACK_CHARGE); DEFINE_MTHP_STAT_ATTR(split, MTHP_STAT_SPLIT); DEFINE_MTHP_STAT_ATTR(split_failed, MTHP_STAT_SPLIT_FAILED); DEFINE_MTHP_STAT_ATTR(split_deferred, MTHP_STAT_SPLIT_DEFERRED); +DEFINE_MTHP_STAT_ATTR(anon_num, MTHP_STAT_NR_ANON); static struct attribute *stats_attrs[] = { &anon_fault_alloc_attr.attr, @@ -591,6 +592,7 @@ static struct attribute *stats_attrs[] = { &split_attr.attr, &split_failed_attr.attr, &split_deferred_attr.attr, + &anon_num_attr.attr, NULL, }; diff --git a/mm/rmap.c b/mm/rmap.c index 901950200957..2b722f26224c 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -1467,6 +1467,7 @@ void folio_add_new_anon_rmap(struct folio *folio, struct vm_area_struct *vma, } __folio_mod_stat(folio, nr, nr_pmdmapped); + mod_mthp_stat(folio_order(folio), MTHP_STAT_NR_ANON, 1); } static __always_inline void __folio_add_file_rmap(struct folio *folio, @@ -1582,6 +1583,8 @@ static __always_inline void __folio_remove_rmap(struct folio *folio, list_empty(&folio->_deferred_list)) deferred_split_folio(folio); __folio_mod_stat(folio, -nr, -nr_pmdmapped); + if (folio_test_anon(folio) && !atomic_read(mapped)) + mod_mthp_stat(folio_order(folio), MTHP_STAT_NR_ANON, -1); /* * It would be tidy to reset folio_test_anon mapping when fully -- 2.34.1