This commit was manufactured by cvs2svn to create branch 'vserver'.

[linux-2.6.git] / mm / readahead.c

diff --git a/mm/readahead.c b/mm/readahead.c
index 9723956..a5e6906 100644 (file)
--- a/mm/readahead.c
+++ b/mm/readahead.c
@@ -28,16 +28,15 @@ struct backing_dev_info default_backing_dev_info = {
 EXPORT_SYMBOL_GPL(default_backing_dev_info);
 
 /*
- * Initialise a struct file's readahead state
+ * Initialise a struct file's readahead state.  Assumes that the caller has
+ * memset *ra to zero.
  */
 void
 file_ra_state_init(struct file_ra_state *ra, struct address_space *mapping)
 {
-       memset(ra, 0, sizeof(*ra));
        ra->ra_pages = mapping->backing_dev_info->ra_pages;
        ra->average = ra->ra_pages / 2;
 }
-EXPORT_SYMBOL(file_ra_state_init);
 
 /*
  * Return max readahead size for this inode in number-of-pages.
@@ -349,7 +348,6 @@ page_cache_readahead(struct address_space *mapping, struct file_ra_state *ra,
                        struct file *filp, unsigned long offset)
 {
        unsigned max;
-       unsigned min;
        unsigned orig_next_size;
        unsigned actual;
        int first_access=0;
@@ -374,7 +372,6 @@ page_cache_readahead(struct address_space *mapping, struct file_ra_state *ra,
        if (max == 0)
                goto out;       /* No readahead */
 
-       min = get_min_readahead(ra);
        orig_next_size = ra->next_size;
 
        if (ra->next_size == 0) {
@@ -386,25 +383,10 @@ page_cache_readahead(struct address_space *mapping, struct file_ra_state *ra,
                first_access=1;
                ra->next_size = max / 2;
                ra->prev_page = offset;
-               ra->serial_cnt++;
+               ra->currnt_wnd_hit++;
                goto do_io;
        }
 
-       if (offset == ra->prev_page + 1) {
-               if (ra->serial_cnt <= (max * 2))
-                       ra->serial_cnt++;
-       } else {
-               /*
-                * to avoid rounding errors, ensure that 'average'
-                * tends towards the value of ra->serial_cnt.
-                */
-               average = ra->average;
-               if (average < ra->serial_cnt) {
-                       average++;
-               }
-               ra->average = (average + ra->serial_cnt) / 2;
-               ra->serial_cnt = 1;
-       }
        ra->prev_page = offset;
 
        if (offset >= ra->start && offset <= (ra->start + ra->size)) {
@@ -413,12 +395,22 @@ page_cache_readahead(struct address_space *mapping, struct file_ra_state *ra,
                 * page beyond the end.  Expand the next readahead size.
                 */
                ra->next_size += 2;
+
+               if (ra->currnt_wnd_hit <= (max * 2))
+                       ra->currnt_wnd_hit++;
        } else {
                /*
                 * A miss - lseek, pagefault, pread, etc.  Shrink the readahead
                 * window.
                 */
                ra->next_size -= 2;
+
+               average = ra->average;
+               if (average < ra->currnt_wnd_hit) {
+                       average++;
+               }
+               ra->average = (average + ra->currnt_wnd_hit) / 2;
+               ra->currnt_wnd_hit = 1;
        }
 
        if ((long)ra->next_size > (long)max)
@@ -470,7 +462,11 @@ do_io:
                          * pages shall be accessed in the next
                          * current window.
                          */
-                       ra->next_size = min(ra->average , (unsigned long)max);
+                       average = ra->average;
+                       if (ra->currnt_wnd_hit > average)
+                               average = (ra->currnt_wnd_hit + ra->average + 1) / 2;
+
+                       ra->next_size = min(average , (unsigned long)max);
                }
                ra->start = offset;
                ra->size = ra->next_size;
@@ -503,8 +499,8 @@ do_io:
                         * random. Hence don't bother to readahead.
                         */
                        average = ra->average;
-                       if (ra->serial_cnt > average)
-                               average = (ra->serial_cnt + ra->average + 1) / 2;
+                       if (ra->currnt_wnd_hit > average)
+                               average = (ra->currnt_wnd_hit + ra->average + 1) / 2;
 
                        if (average > max) {
                                ra->ahead_start = ra->start + ra->size;
@@ -552,6 +548,7 @@ void handle_ra_miss(struct address_space *mapping,
                                ra->size = max;
                                ra->ahead_start = 0;
                                ra->ahead_size = 0;
+                               ra->average = max / 2;
                        }
                }
                ra->prev_page = offset;
@@ -574,6 +571,6 @@ unsigned long max_sane_readahead(unsigned long nr)
        unsigned long inactive;
        unsigned long free;
 
-       get_zone_counts(&active, &inactive, &free);
+       __get_zone_counts(&active, &inactive, &free, NODE_DATA(numa_node_id()));
        return min(nr, (inactive + free) / 2);
 }