[PATCH 1/8] compacting file_ra_state

[Fengguang Wu]

Use 'unsigned int' instead of 'unsigned long' for readahead sizes.

This helps reduce memory consumption on 64bit CPU when
a lot of files are opened.

CC: Andi Kleen <andi@xxxxxxxxxxxxxx>
Signed-off-by: Fengguang Wu <wfg@xxxxxxxxxxxxxxxx>
---
 include/linux/fs.h |    8 ++++----
 mm/readahead.c     |    2 +-
 2 files changed, 5 insertions(+), 5 deletions(-)

--- linux-2.6.22-git15.orig/include/linux/fs.h
+++ linux-2.6.22-git15/include/linux/fs.h
@@ -697,12 +697,12 @@ struct fown_struct {
  * Track a single file's readahead state
  */
 struct file_ra_state {
-	pgoff_t start;                  /* where readahead started */
-	unsigned long size;             /* # of readahead pages */
-	unsigned long async_size;       /* do asynchronous readahead when
+	pgoff_t start;			/* where readahead started */
+	unsigned int size;		/* # of readahead pages */
+	unsigned int async_size;	/* do asynchronous readahead when
 					   there are only # of pages ahead */
 
-	unsigned long ra_pages;		/* Maximum readahead window */
+	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 */
 	unsigned long prev_index;	/* Cache last read() position */
--- linux-2.6.22-git15.orig/mm/readahead.c
+++ linux-2.6.22-git15/mm/readahead.c
@@ -350,7 +350,7 @@ ondemand_readahead(struct address_space 
 		   bool hit_readahead_marker, pgoff_t offset,
 		   unsigned long req_size)
 {
-	unsigned long max;	/* max readahead pages */
+	int max;	/* max readahead pages */
 	int sequential;
 
 	max = ra->ra_pages;

--
-
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