Skip to content

Commit

Permalink
mm, shmem: add vmstat for hugepage fallback
Browse files Browse the repository at this point in the history
The existing thp_fault_fallback indicates when thp attempts to allocate a
hugepage but fails, or if the hugepage cannot be charged to the mem cgroup
hierarchy.

Extend this to shmem as well.  Adds a new thp_file_fallback to complement
thp_file_alloc that gets incremented when a hugepage is attempted to be
allocated but fails, or if it cannot be charged to the mem cgroup
hierarchy.

Additionally, remove the check for CONFIG_TRANSPARENT_HUGE_PAGECACHE from
shmem_alloc_hugepage() since it is only called with this configuration
option.

Signed-off-by: David Rientjes <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Reviewed-by: Yang Shi <[email protected]>
Acked-by: Kirill A. Shutemov <[email protected]>
Cc: Mike Rapoport <[email protected]>
Cc: Jeremy Cline <[email protected]>
Cc: Andrea Arcangeli <[email protected]>
Cc: Mike Kravetz <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Linus Torvalds <[email protected]>
  • Loading branch information
rientjes authored and torvalds committed Apr 7, 2020
1 parent 6aeff24 commit dcdf11e
Show file tree
Hide file tree
Showing 4 changed files with 13 additions and 4 deletions.
4 changes: 4 additions & 0 deletions Documentation/admin-guide/mm/transhuge.rst
Original file line number Diff line number Diff line change
Expand Up @@ -319,6 +319,10 @@ thp_file_alloc
is incremented every time a file huge page is successfully
allocated.

thp_file_fallback
is incremented if a file huge page is attempted to be allocated
but fails and instead falls back to using small pages.

thp_file_mapped
is incremented every time a file huge page is mapped into
user address space.
Expand Down
2 changes: 2 additions & 0 deletions include/linux/vm_event_item.h
Original file line number Diff line number Diff line change
Expand Up @@ -76,6 +76,7 @@ enum vm_event_item { PGPGIN, PGPGOUT, PSWPIN, PSWPOUT,
THP_COLLAPSE_ALLOC,
THP_COLLAPSE_ALLOC_FAILED,
THP_FILE_ALLOC,
THP_FILE_FALLBACK,
THP_FILE_MAPPED,
THP_SPLIT_PAGE,
THP_SPLIT_PAGE_FAILED,
Expand Down Expand Up @@ -115,6 +116,7 @@ enum vm_event_item { PGPGIN, PGPGOUT, PSWPIN, PSWPOUT,

#ifndef CONFIG_TRANSPARENT_HUGEPAGE
#define THP_FILE_ALLOC ({ BUILD_BUG(); 0; })
#define THP_FILE_FALLBACK ({ BUILD_BUG(); 0; })
#define THP_FILE_MAPPED ({ BUILD_BUG(); 0; })
#endif

Expand Down
10 changes: 6 additions & 4 deletions mm/shmem.c
Original file line number Diff line number Diff line change
Expand Up @@ -1472,9 +1472,6 @@ static struct page *shmem_alloc_hugepage(gfp_t gfp,
pgoff_t hindex;
struct page *page;

if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGE_PAGECACHE))
return NULL;

hindex = round_down(index, HPAGE_PMD_NR);
if (xa_find(&mapping->i_pages, &hindex, hindex + HPAGE_PMD_NR - 1,
XA_PRESENT))
Expand All @@ -1486,6 +1483,8 @@ static struct page *shmem_alloc_hugepage(gfp_t gfp,
shmem_pseudo_vma_destroy(&pvma);
if (page)
prep_transhuge_page(page);
else
count_vm_event(THP_FILE_FALLBACK);
return page;
}

Expand Down Expand Up @@ -1871,8 +1870,11 @@ static int shmem_getpage_gfp(struct inode *inode, pgoff_t index,

error = mem_cgroup_try_charge_delay(page, charge_mm, gfp, &memcg,
PageTransHuge(page));
if (error)
if (error) {
if (PageTransHuge(page))
count_vm_event(THP_FILE_FALLBACK);
goto unacct;
}
error = shmem_add_to_page_cache(page, mapping, hindex,
NULL, gfp & GFP_RECLAIM_MASK);
if (error) {
Expand Down
1 change: 1 addition & 0 deletions mm/vmstat.c
Original file line number Diff line number Diff line change
Expand Up @@ -1259,6 +1259,7 @@ const char * const vmstat_text[] = {
"thp_collapse_alloc",
"thp_collapse_alloc_failed",
"thp_file_alloc",
"thp_file_fallback",
"thp_file_mapped",
"thp_split_page",
"thp_split_page_failed",
Expand Down

0 comments on commit dcdf11e

Please sign in to comment.