openkylin
/
linux
mirror of https://gitee.com/openkylin/linux.git
9
0
Fork 0
Code Issues Projects Releases Wiki Activity

mm: remove redundant compound_head() calling 

There is a READ_ONCE() in the macro of compound_head(), which will prevent
compiler from optimizing the code when there are more than once calling of
it in a function.  Remove the redundant calling of compound_head() from
page_to_index() and page_add_file_rmap() for better code generation.

Link: https://lkml.kernel.org/r/20210811101431.83940-1-songmuchun@bytedance.com
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Reviewed-by: David Howells <dhowells@redhat.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: William Kucharski <william.kucharski@oracle.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Muchun Song 2021-09-07 19:55:55 -07:00 committed by Linus Torvalds
parent 5ef5f81019
commit fe3df441ef
2 changed files with 7 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

7
include/linux/pagemap.h
View File

@ -521,18 +521,17 @@ static inline struct page *read_mapping_page(struct address_space *mapping,
*/
static inline pgoff_t page_to_index(struct page *page)
{
pgoff_t pgoff;
struct page *head;
if (likely(!PageTransTail(page)))
return page->index;
head = compound_head(page);
/*
* We don't initialize ->index for tail pages: calculate based on
* head page
*/
pgoff = compound_head(page)->index;
pgoff += page - compound_head(page);
return pgoff;
return head->index + page - head;
}
extern pgoff_t hugetlb_basepage_index(struct page *page);

6
mm/rmap.c
View File

@ -1230,11 +1230,13 @@ void page_add_file_rmap(struct page *page, bool compound)
nr_pages);
} else {
if (PageTransCompound(page) && page_mapping(page)) {
struct page *head = compound_head(page);
VM_WARN_ON_ONCE(!PageLocked(page));
SetPageDoubleMap(compound_head(page));
SetPageDoubleMap(head);
if (PageMlocked(page))
clear_page_mlock(compound_head(page));
clear_page_mlock(head);
}
if (!atomic_inc_and_test(&page->_mapcount))
goto out;