The patch titled
Subject: include/linux/page-flags.h: force inlining of selected page flag modifications
has been added to the -mm tree. Its filename is
force-inlining-of-selected-page-flag-modifications.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/force-inlining-of-selected-page-flag-modifications.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/force-inlining-of-selected-page-flag-modifications.patch
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*** Remember to use Documentation/SubmitChecklist when testing your code ***
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------------------------------------------------------
From: Denys Vlasenko <dvlasenk@xxxxxxxxxx>
Subject: include/linux/page-flags.h: force inlining of selected page flag modifications
Sometimes gcc mysteriously doesn't inline
very small functions we expect to be inlined. See
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66122
With this .config:
http://busybox.net/~vda/kernel_config_OPTIMIZE_INLINING_and_Os,
the following functions get deinlined many times.
Examples of disassembly:
<SetPageUptodate> (43 copies, 141 calls):
55 push %rbp
48 89 e5 mov %rsp,%rbp
f0 80 0f 08 lock orb $0x8,(%rdi)
5d pop %rbp
c3 retq
<PagePrivate> (10 copies, 134 calls):
48 8b 07 mov (%rdi),%rax
55 push %rbp
48 89 e5 mov %rsp,%rbp
48 c1 e8 0b shr $0xb,%rax
83 e0 01 and $0x1,%eax
5d pop %rbp
c3 retq
This patch fixes this via s/inline/__always_inline/.
Code size decrease after the patch is ~7k:
text data bss dec hex filename
92125002 20826048 36417536 149368586 8e72f0a vmlinux
92118087 20826112 36417536 149361735 8e71447 vmlinux7_pageops_after
Signed-off-by: Denys Vlasenko <dvlasenk@xxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Thomas Graf <tgraf@xxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/page-flags.h | 30 +++++++++++++++---------------
1 file changed, 15 insertions(+), 15 deletions(-)
diff -puN include/linux/page-flags.h~force-inlining-of-selected-page-flag-modifications include/linux/page-flags.h
--- a/include/linux/page-flags.h~force-inlining-of-selected-page-flag-modifications
+++ a/include/linux/page-flags.h
@@ -144,12 +144,12 @@ static inline struct page *compound_head
return page;
}
-static inline int PageTail(struct page *page)
+static __always_inline int PageTail(struct page *page)
{
return READ_ONCE(page->compound_head) & 1;
}
-static inline int PageCompound(struct page *page)
+static __always_inline int PageCompound(struct page *page)
{
return test_bit(PG_head, &page->flags) || PageTail(page);
}
@@ -184,31 +184,31 @@ static inline int PageCompound(struct pa
* Macros to create function definitions for page flags
*/
#define TESTPAGEFLAG(uname, lname, policy) \
-static inline int Page##uname(struct page *page) \
+static __always_inline int Page##uname(struct page *page) \
{ return test_bit(PG_##lname, &policy(page, 0)->flags); }
#define SETPAGEFLAG(uname, lname, policy) \
-static inline void SetPage##uname(struct page *page) \
+static __always_inline void SetPage##uname(struct page *page) \
{ set_bit(PG_##lname, &policy(page, 1)->flags); }
#define CLEARPAGEFLAG(uname, lname, policy) \
-static inline void ClearPage##uname(struct page *page) \
+static __always_inline void ClearPage##uname(struct page *page) \
{ clear_bit(PG_##lname, &policy(page, 1)->flags); }
#define __SETPAGEFLAG(uname, lname, policy) \
-static inline void __SetPage##uname(struct page *page) \
+static __always_inline void __SetPage##uname(struct page *page) \
{ __set_bit(PG_##lname, &policy(page, 1)->flags); }
#define __CLEARPAGEFLAG(uname, lname, policy) \
-static inline void __ClearPage##uname(struct page *page) \
+static __always_inline void __ClearPage##uname(struct page *page) \
{ __clear_bit(PG_##lname, &policy(page, 1)->flags); }
#define TESTSETFLAG(uname, lname, policy) \
-static inline int TestSetPage##uname(struct page *page) \
+static __always_inline int TestSetPage##uname(struct page *page) \
{ return test_and_set_bit(PG_##lname, &policy(page, 1)->flags); }
#define TESTCLEARFLAG(uname, lname, policy) \
-static inline int TestClearPage##uname(struct page *page) \
+static __always_inline int TestClearPage##uname(struct page *page) \
{ return test_and_clear_bit(PG_##lname, &policy(page, 1)->flags); }
#define PAGEFLAG(uname, lname, policy) \
@@ -371,7 +371,7 @@ PAGEFLAG(Idle, idle, PF_ANY)
#define PAGE_MAPPING_KSM 2
#define PAGE_MAPPING_FLAGS (PAGE_MAPPING_ANON | PAGE_MAPPING_KSM)
-static inline int PageAnon(struct page *page)
+static __always_inline int PageAnon(struct page *page)
{
page = compound_head(page);
return ((unsigned long)page->mapping & PAGE_MAPPING_ANON) != 0;
@@ -384,7 +384,7 @@ static inline int PageAnon(struct page *
* is found in VM_MERGEABLE vmas. It's a PageAnon page, pointing not to any
* anon_vma, but to that page's node of the stable tree.
*/
-static inline int PageKsm(struct page *page)
+static __always_inline int PageKsm(struct page *page)
{
page = compound_head(page);
return ((unsigned long)page->mapping & PAGE_MAPPING_FLAGS) ==
@@ -415,14 +415,14 @@ static inline int PageUptodate(struct pa
return ret;
}
-static inline void __SetPageUptodate(struct page *page)
+static __always_inline void __SetPageUptodate(struct page *page)
{
VM_BUG_ON_PAGE(PageTail(page), page);
smp_wmb();
__set_bit(PG_uptodate, &page->flags);
}
-static inline void SetPageUptodate(struct page *page)
+static __always_inline void SetPageUptodate(struct page *page)
{
VM_BUG_ON_PAGE(PageTail(page), page);
/*
@@ -456,12 +456,12 @@ static inline void set_page_writeback_ke
__PAGEFLAG(Head, head, PF_ANY) CLEARPAGEFLAG(Head, head, PF_ANY)
-static inline void set_compound_head(struct page *page, struct page *head)
+static __always_inline void set_compound_head(struct page *page, struct page *head)
{
WRITE_ONCE(page->compound_head, (unsigned long)head + 1);
}
-static inline void clear_compound_head(struct page *page)
+static __always_inline void clear_compound_head(struct page *page)
{
WRITE_ONCE(page->compound_head, 0);
}
_
Patches currently in -mm which might be from dvlasenk@xxxxxxxxxx are
bufferhead-force-inlining-of-buffer-head-flag-operations.patch
force-inlining-of-selected-page-flag-modifications.patch
asm-generic-force-inlining-of-some-atomic_long-operations.patch
force-inlining-of-some-byteswap-operations.patch
force-inlining-of-unaligned-byteswap-operations.patch
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