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authorWu Fengguang <fengguang.wu@intel.com>2009-06-16 15:31:19 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2009-06-16 19:47:28 -0700
commit1ebf26a9b338534def47f307c6c8694b6dfc0a79 (patch)
tree26829a8cc727388c0da8eea6de38d7ba0eda2a47 /include
parentbb1f17b0372de93758653ca3454bc0df18dc2e5c (diff)
downloadlinux-1ebf26a9b338534def47f307c6c8694b6dfc0a79.tar.bz2
readahead: make mmap_miss an unsigned int
This makes the performance impact of possible mmap_miss wrap around to be temporary and tolerable: i.e. MMAP_LOTSAMISS=100 extra readarounds. Otherwise if ever mmap_miss wraps around to negative, it takes INT_MAX cache misses to bring it back to normal state. During the time mmap readaround will be _enabled_ for whatever wild random workload. That's almost permanent performance impact. Signed-off-by: Wu Fengguang <fengguang.wu@intel.com> Cc: Ying Han <yinghan@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include')
-rw-r--r--include/linux/fs.h2
1 files changed, 1 insertions, 1 deletions
diff --git a/include/linux/fs.h b/include/linux/fs.h
index ede84fa7da5d..8146e0264ef9 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -879,7 +879,7 @@ struct file_ra_state {
there are only # of pages ahead */
unsigned int ra_pages; /* Maximum readahead window */
- int mmap_miss; /* Cache miss stat for mmap accesses */
+ unsigned int mmap_miss; /* Cache miss stat for mmap accesses */
loff_t prev_pos; /* Cache last read() position */
};