diff options
| author | Baolin Wang <baolin.wang@linux.alibaba.com> | 2024-06-11 18:11:07 +0800 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2024-07-03 19:30:04 -0700 |
| commit | 4b98995530b77a97912230d8e1564ba7738db19c (patch) | |
| tree | 50f524472b5759befed0cb9404356b81d0bd2359 /Documentation/admin-guide/mm | |
| parent | 3d95bc21cea558c7cdb2942b4d0223a571e93f27 (diff) | |
mm: shmem: add multi-size THP sysfs interface for anonymous shmem
To support the use of mTHP with anonymous shmem, add a new sysfs interface
'shmem_enabled' in the '/sys/kernel/mm/transparent_hugepage/hugepages-kB/'
directory for each mTHP to control whether shmem is enabled for that mTHP,
with a value similar to the top level 'shmem_enabled', which can be set
to: "always", "inherit (to inherit the top level setting)", "within_size",
"advise", "never". An 'inherit' option is added to ensure compatibility
with these global settings, and the options 'force' and 'deny' are
dropped, which are rather testing artifacts from the old ages.
By default, PMD-sized hugepages have enabled="inherit" and all other
hugepage sizes have enabled="never" for
'/sys/kernel/mm/transparent_hugepage/hugepages-xxkB/shmem_enabled'.
In addition, if top level value is 'force', then only PMD-sized hugepages
have enabled="inherit", otherwise configuration will be failed and vice
versa. That means now we will avoid using non-PMD sized THP to override
the global huge allocation.
[baolin.wang@linux.alibaba.com: fix transhuge.rst indentation]
Link: https://lkml.kernel.org/r/b189d815-998b-4dfd-ba89-218ff51313f8@linux.alibaba.com
[akpm@linux-foundation.org: reflow transhuge.rst addition to 80 cols]
[baolin.wang@linux.alibaba.com: move huge_shmem_orders_lock under CONFIG_SYSFS]
Link: https://lkml.kernel.org/r/eb34da66-7f12-44f3-a39e-2bcc90c33354@linux.alibaba.com
[akpm@linux-foundation.org: huge_memory.c needs mm_types.h]
Link: https://lkml.kernel.org/r/ffddfa8b3cb4266ff963099ab78cfd7184c57ac7.1718090413.git.baolin.wang@linux.alibaba.com
Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Barry Song <v-songbaohua@oppo.com>
Cc: Daniel Gomez <da.gomez@samsung.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Lance Yang <ioworker0@gmail.com>
Cc: Pankaj Raghav <p.raghav@samsung.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'Documentation/admin-guide/mm')
| -rw-r--r-- | Documentation/admin-guide/mm/transhuge.rst | 25 |
1 files changed, 25 insertions, 0 deletions
diff --git a/Documentation/admin-guide/mm/transhuge.rst b/Documentation/admin-guide/mm/transhuge.rst index d414d3f5592a..e7232b46fe14 100644 --- a/Documentation/admin-guide/mm/transhuge.rst +++ b/Documentation/admin-guide/mm/transhuge.rst @@ -332,6 +332,31 @@ deny force Force the huge option on for all - very useful for testing; +Shmem can also use "multi-size THP" (mTHP) by adding a new sysfs knob to +control mTHP allocation: +'/sys/kernel/mm/transparent_hugepage/hugepages-<size>kB/shmem_enabled', +and its value for each mTHP is essentially consistent with the global +setting. An 'inherit' option is added to ensure compatibility with these +global settings. Conversely, the options 'force' and 'deny' are dropped, +which are rather testing artifacts from the old ages. + +always + Attempt to allocate <size> huge pages every time we need a new page; + +inherit + Inherit the top-level "shmem_enabled" value. By default, PMD-sized hugepages + have enabled="inherit" and all other hugepage sizes have enabled="never"; + +never + Do not allocate <size> huge pages; + +within_size + Only allocate <size> huge page if it will be fully within i_size. + Also respect fadvise()/madvise() hints; + +advise + Only allocate <size> huge pages if requested with fadvise()/madvise(); + Need of application restart =========================== |