diff options
| author |   Barry Song <v-songbaohua@oppo.com> | 2024-08-24 13:04:41 +1200 |
|---|---|---|
| committer |   Andrew Morton <akpm@linux-foundation.org> | 2024-09-09 16:38:57 -0700 |
| commit | 8175ebfd302abe6fbdca9037f763ecbfdb8db572 (patch) | |
| tree | 6af43876f366d0523bdbed959fb1ba58eea8a059 /Documentation/admin-guide | |
| parent | mm: count the number of anonymous THPs per size (diff) | |
| download | wireguard-linux-8175ebfd302abe6fbdca9037f763ecbfdb8db572.tar.xz wireguard-linux-8175ebfd302abe6fbdca9037f763ecbfdb8db572.zip | |
mm: count the number of partially mapped anonymous THPs per size
When a THP is added to the deferred_list due to partially mapped, its
partial pages are unused, leading to wasted memory and potentially
increasing memory reclamation pressure.
Detailing the specifics of how unmapping occurs is quite difficult and not
that useful, so we adopt a simple approach: each time a THP enters the
deferred_list, we increment the count by 1; whenever it leaves for any
reason, we decrement the count by 1.
Link: https://lkml.kernel.org/r/20240824010441.21308-3-21cnbao@gmail.com
Signed-off-by: Barry Song <v-songbaohua@oppo.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Chris Li <chrisl@kernel.org>
Cc: Chuanhua Han <hanchuanhua@oppo.com>
Cc: Kairui Song <kasong@tencent.com>
Cc: Kalesh Singh <kaleshsingh@google.com>
Cc: Lance Yang <ioworker0@gmail.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Shuai Yuan <yuanshuai@oppo.com>
Cc: Usama Arif <usamaarif642@gmail.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'Documentation/admin-guide')
| -rw-r--r-- | Documentation/admin-guide/mm/transhuge.rst | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/Documentation/admin-guide/mm/transhuge.rst b/Documentation/admin-guide/mm/transhuge.rst index d6874234a09a..56a086900651 100644 --- a/Documentation/admin-guide/mm/transhuge.rst +++ b/Documentation/admin-guide/mm/transhuge.rst @@ -556,6 +556,13 @@ nr_anon might be currently entirely mapped or have partially unmapped/unused subpages. +nr_anon_partially_mapped + the number of anonymous THP which are likely partially mapped, possibly + wasting memory, and have been queued for deferred memory reclamation. + Note that in corner some cases (e.g., failed migration), we might detect + an anonymous THP as "partially mapped" and count it here, even though it + is not actually partially mapped anymore. + 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 |