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| author | Kirill A. Shutemov <kirill.shutemov@linux.intel.com> | 2016-07-27 00:26:13 +0200 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2016-07-27 01:19:19 +0200 |
| commit | 5a6e75f8110c97e2a5488894d4e922187e6cb343 (patch) | |
| tree | f4ecded42322672de8b4afed65d40e20ef17bcb6 /mm/huge_memory.c | |
| parent | mm, rmap: account shmem thp pages (diff) | |
| download | linux-5a6e75f8110c97e2a5488894d4e922187e6cb343.tar.xz linux-5a6e75f8110c97e2a5488894d4e922187e6cb343.zip | |
shmem: prepare huge= mount option and sysfs knob
This patch adds new mount option "huge=". It can have following values:
- "always":
Attempt to allocate huge pages every time we need a new page;
- "never":
Do not allocate huge pages;
- "within_size":
Only allocate huge page if it will be fully within i_size.
Also respect fadvise()/madvise() hints;
- "advise:
Only allocate huge pages if requested with fadvise()/madvise();
Default is "never" for now.
"mount -o remount,huge= /mountpoint" works fine after mount: remounting
huge=never will not attempt to break up huge pages at all, just stop
more from being allocated.
No new config option: put this under CONFIG_TRANSPARENT_HUGEPAGE, which
is the appropriate option to protect those who don't want the new bloat,
and with which we shall share some pmd code.
Prohibit the option when !CONFIG_TRANSPARENT_HUGEPAGE, just as mpol is
invalid without CONFIG_NUMA (was hidden in mpol_parse_str(): make it
explicit).
Allow enabling THP only if the machine has_transparent_hugepage().
But what about Shmem with no user-visible mount? SysV SHM, memfds,
shared anonymous mmaps (of /dev/zero or MAP_ANONYMOUS), GPU drivers' DRM
objects, Ashmem. Though unlikely to suit all usages, provide sysfs knob
/sys/kernel/mm/transparent_hugepage/shmem_enabled to experiment with
huge on those.
And allow shmem_enabled two further values:
- "deny":
For use in emergencies, to force the huge option off from
all mounts;
- "force":
Force the huge option on for all - very useful for testing;
Based on patch by Hugh Dickins.
Link: http://lkml.kernel.org/r/1466021202-61880-28-git-send-email-kirill.shutemov@linux.intel.com
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/huge_memory.c')
| -rw-r--r-- | mm/huge_memory.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 6c524984931b..cabd53dac5b9 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -442,6 +442,9 @@ static struct attribute *hugepage_attr[] = { &enabled_attr.attr, &defrag_attr.attr, &use_zero_page_attr.attr, +#ifdef CONFIG_SHMEM + &shmem_enabled_attr.attr, +#endif #ifdef CONFIG_DEBUG_VM &debug_cow_attr.attr, #endif |