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Subject[PATCH 2/7] readahead: mmap read-around simplification
Fold file_ra_state.mmap_hit into file_ra_state.mmap_miss
and make it an int.

Signed-off-by: Fengguang Wu <wfg@mail.ustc.edu.cn>
---
include/linux/fs.h | 3 +--
mm/filemap.c | 4 ++--
2 files changed, 3 insertions(+), 4 deletions(-)
--- linux-2.6.22-rc6-mm1.orig/include/linux/fs.h
+++ linux-2.6.22-rc6-mm1/include/linux/fs.h
@@ -777,8 +777,7 @@ struct file_ra_state {
there are only # of pages ahead */

unsigned int ra_pages; /* Maximum readahead window */
- unsigned long mmap_hit; /* Cache hit stat for mmap accesses */
- unsigned long mmap_miss; /* Cache miss stat for mmap accesses */
+ int mmap_miss; /* Cache miss stat for mmap accesses */
unsigned long prev_index; /* Cache last read() position */
unsigned int prev_offset; /* Offset where last read() ended in a page */
};
--- linux-2.6.22-rc6-mm1.orig/mm/filemap.c
+++ linux-2.6.22-rc6-mm1/mm/filemap.c
@@ -1389,7 +1389,7 @@ retry_find:
* Do we miss much more than hit in this file? If so,
* stop bothering with read-ahead. It will only hurt.
*/
- if (ra->mmap_miss > ra->mmap_hit + MMAP_LOTSAMISS)
+ if (ra->mmap_miss > MMAP_LOTSAMISS)
goto no_cached_page;

/*
@@ -1415,7 +1415,7 @@ retry_find:
}

if (!did_readaround)
- ra->mmap_hit++;
+ ra->mmap_miss--;

/*
* We have a locked page in the page cache, now we need to check
--
-
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