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authorFengguang Wu <wfg@mail.ustc.edu.cn>2007-07-19 01:47:55 -0700
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-07-19 10:04:43 -0700
commitd77c2d7cc5126639a47d73300b40d461f2811a0f (patch)
treed02b32ca92fde9a04be9bee0f0b7c8961479448c
parent2ba2d00363975242dee9bb22cf798b487e3cd61e (diff)
downloadop-kernel-dev-d77c2d7cc5126639a47d73300b40d461f2811a0f.zip
op-kernel-dev-d77c2d7cc5126639a47d73300b40d461f2811a0f.tar.gz
readahead: introduce PG_readahead
Introduce a new page flag: PG_readahead. It acts as a look-ahead mark, which tells the page reader: Hey, it's time to invoke the read-ahead logic. For the sake of I/O pipelining, don't wait until it runs out of cached pages! Signed-off-by: Fengguang Wu <wfg@mail.ustc.edu.cn> Cc: Steven Pratt <slpratt@austin.ibm.com> Cc: Ram Pai <linuxram@us.ibm.com> Cc: Rusty Russell <rusty@rustcorp.com.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--include/linux/page-flags.h5
-rw-r--r--mm/page_alloc.c2
2 files changed, 6 insertions, 1 deletions
diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
index 731cd2a..709d92f 100644
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h
@@ -83,6 +83,7 @@
#define PG_private 11 /* If pagecache, has fs-private data */
#define PG_writeback 12 /* Page is under writeback */
+#define PG_readahead 13 /* Reminder to do async read-ahead */
#define PG_compound 14 /* Part of a compound page */
#define PG_swapcache 15 /* Swap page: swp_entry_t in private */
@@ -226,6 +227,10 @@ static inline void SetPageUptodate(struct page *page)
#define SetPageMappedToDisk(page) set_bit(PG_mappedtodisk, &(page)->flags)
#define ClearPageMappedToDisk(page) clear_bit(PG_mappedtodisk, &(page)->flags)
+#define PageReadahead(page) test_bit(PG_readahead, &(page)->flags)
+#define SetPageReadahead(page) set_bit(PG_readahead, &(page)->flags)
+#define ClearPageReadahead(page) clear_bit(PG_readahead, &(page)->flags)
+
#define PageReclaim(page) test_bit(PG_reclaim, &(page)->flags)
#define SetPageReclaim(page) set_bit(PG_reclaim, &(page)->flags)
#define ClearPageReclaim(page) clear_bit(PG_reclaim, &(page)->flags)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index e2a10b9..2165be9 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -617,7 +617,7 @@ static int prep_new_page(struct page *page, int order, gfp_t gfp_flags)
if (PageReserved(page))
return 1;
- page->flags &= ~(1 << PG_uptodate | 1 << PG_error |
+ page->flags &= ~(1 << PG_uptodate | 1 << PG_error | 1 << PG_readahead |
1 << PG_referenced | 1 << PG_arch_1 |
1 << PG_owner_priv_1 | 1 << PG_mappedtodisk);
set_page_private(page, 0);
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