From: Matthew Wilcox <willy@infradead.org>
To: Andrew Morton <akpm@linux-foundation.org>,
Vlastimil Babka <vbabka@suse.cz>,
linux-mm@kvack.org
Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Subject: [PATCH] mm: Make PageType more efficient
Date: Tue, 10 Mar 2020 11:56:09 -0700 [thread overview]
Message-ID: <20200310185609.5401-1-willy@infradead.org> (raw)
From: "Matthew Wilcox (Oracle)" <willy@infradead.org>
PageType is a little hard for GCC to reason about, By checking
((~A) & flag) instead of (flag & (A | MASK) == MASK), GCC can do
better optimisations, saving 652 bytes in page_alloc.o (which is
a heavy user of PageBuddy).
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
include/linux/page-flags.h | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
index 1bf83c8fcaa7..8fc0876e2794 100644
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h
@@ -725,14 +725,14 @@ PAGEFLAG_FALSE(DoubleMap)
#define PG_table 0x00000400
#define PG_guard 0x00000800
-#define PageType(page, flag) \
- ((page->page_type & (PAGE_TYPE_BASE | flag)) == PAGE_TYPE_BASE)
-
static inline int page_has_type(struct page *page)
{
return (int)page->page_type < PAGE_MAPCOUNT_RESERVE;
}
+#define PageType(page, flag) \
+ (page_has_type(page) && (~page->page_type & flag))
+
#define PAGE_TYPE_OPS(uname, lname) \
static __always_inline int Page##uname(struct page *page) \
{ \
--
2.25.1
next reply other threads:[~2020-03-10 18:56 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-10 18:56 Matthew Wilcox [this message]
2020-03-10 20:17 ` [PATCH] mm: Make PageType more efficient Alexander Duyck
2020-03-10 20:37 ` Matthew Wilcox
2020-03-10 21:50 ` Alexander Duyck
2020-03-11 13:13 ` Matthew Wilcox
2020-03-11 17:14 ` Ira Weiny
2020-03-11 17:22 ` Alexander Duyck
2020-03-11 1:10 ` Andrew Morton
2020-03-11 13:21 ` Matthew Wilcox
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