Branch HEAD

[fs/lustre-release.git] / lustre / llite / llite_internal.h

diff --git a/lustre/llite/llite_internal.h b/lustre/llite/llite_internal.h
index 492a0eb..de34d52 100644 (file)
--- a/lustre/llite/llite_internal.h
+++ b/lustre/llite/llite_internal.h
@@ -390,6 +390,27 @@ struct ll_readahead_state {
          * protected by ->ras_lock.
          */
         struct list_head ras_read_beads;
+        /* 
+         * The following 3 items are used for detecting the stride I/O
+         * mode. 
+        * In stride I/O mode, 
+         * ...............|-----data-----|****gap*****|--------|******|.... 
+         *    offset      |-stride_pages-|-stride_gap-| 
+         * ras_stride_offset = offset;
+         * ras_stride_length = stride_pages + stride_gap;
+         * ras_stride_pages = stride_pages;
+         * Note: all these three items are counted by pages.
+         */
+        unsigned long ras_stride_length;
+        unsigned long ras_stride_pages;
+        pgoff_t ras_stride_offset;
+        /* 
+         * number of consecutive stride request count, and it is similar as
+         * ras_consecutive_requests, but used for stride I/O mode.
+         * Note: only more than 2 consecutive stride request are detected,
+         * stride read-ahead will be enable
+         */
+        unsigned long ras_consecutive_stride_requests;
 };
 
 struct ll_file_dir {