[PATCH] swap: show span of swap extents
The "Adding %dk swap" message shows the number of swap extents, as a guide to
how fragmented the swapfile may be. But a useful further guide is what total
extent they span across (sometimes scarily large).
And there's no need to keep nr_extents in swap_info: it's unused after the
initial message, so save a little space by keeping it on stack.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/mm/swapfile.c b/mm/swapfile.c
index 73521d3..d4da84e 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -854,7 +854,6 @@
list_del(&se->list);
kfree(se);
}
- sis->nr_extents = 0;
}
/*
@@ -893,8 +892,7 @@
new_se->start_block = start_block;
list_add_tail(&new_se->list, &sis->extent_list);
- sis->nr_extents++;
- return 0;
+ return 1;
}
/*
@@ -928,7 +926,7 @@
* This is extremely effective. The average number of iterations in
* map_swap_page() has been measured at about 0.3 per page. - akpm.
*/
-static int setup_swap_extents(struct swap_info_struct *sis)
+static int setup_swap_extents(struct swap_info_struct *sis, sector_t *span)
{
struct inode *inode;
unsigned blocks_per_page;
@@ -936,11 +934,15 @@
unsigned blkbits;
sector_t probe_block;
sector_t last_block;
+ sector_t lowest_block = -1;
+ sector_t highest_block = 0;
+ int nr_extents = 0;
int ret;
inode = sis->swap_file->f_mapping->host;
if (S_ISBLK(inode->i_mode)) {
ret = add_swap_extent(sis, 0, sis->max, 0);
+ *span = sis->pages;
goto done;
}
@@ -985,19 +987,28 @@
}
}
+ first_block >>= (PAGE_SHIFT - blkbits);
+ if (page_no) { /* exclude the header page */
+ if (first_block < lowest_block)
+ lowest_block = first_block;
+ if (first_block > highest_block)
+ highest_block = first_block;
+ }
+
/*
* We found a PAGE_SIZE-length, PAGE_SIZE-aligned run of blocks
*/
- ret = add_swap_extent(sis, page_no, 1,
- first_block >> (PAGE_SHIFT - blkbits));
- if (ret)
+ ret = add_swap_extent(sis, page_no, 1, first_block);
+ if (ret < 0)
goto out;
+ nr_extents += ret;
page_no++;
probe_block += blocks_per_page;
reprobe:
continue;
}
- ret = 0;
+ ret = nr_extents;
+ *span = 1 + highest_block - lowest_block;
if (page_no == 0)
page_no = 1; /* force Empty message */
sis->max = page_no;
@@ -1265,6 +1276,8 @@
union swap_header *swap_header = NULL;
int swap_header_version;
int nr_good_pages = 0;
+ int nr_extents;
+ sector_t span;
unsigned long maxpages = 1;
int swapfilesize;
unsigned short *swap_map;
@@ -1300,7 +1313,6 @@
nr_swapfiles = type+1;
INIT_LIST_HEAD(&p->extent_list);
p->flags = SWP_USED;
- p->nr_extents = 0;
p->swap_file = NULL;
p->old_block_size = 0;
p->swap_map = NULL;
@@ -1477,9 +1489,11 @@
p->swap_map[0] = SWAP_MAP_BAD;
p->max = maxpages;
p->pages = nr_good_pages;
- error = setup_swap_extents(p);
- if (error)
+ nr_extents = setup_swap_extents(p, &span);
+ if (nr_extents < 0) {
+ error = nr_extents;
goto bad_swap;
+ }
nr_good_pages = p->pages;
}
if (!nr_good_pages) {
@@ -1494,9 +1508,11 @@
p->flags = SWP_ACTIVE;
nr_swap_pages += nr_good_pages;
total_swap_pages += nr_good_pages;
- printk(KERN_INFO "Adding %dk swap on %s. Priority:%d extents:%d\n",
- nr_good_pages<<(PAGE_SHIFT-10), name,
- p->prio, p->nr_extents);
+
+ printk(KERN_INFO "Adding %dk swap on %s. "
+ "Priority:%d extents:%d across:%lluk\n",
+ nr_good_pages<<(PAGE_SHIFT-10), name, p->prio,
+ nr_extents, (unsigned long long)span<<(PAGE_SHIFT-10));
/* insert swap space into swap_list: */
prev = -1;