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UBIFS: improve garbage collection 

Make garbage collection try to keep data nodes from the same
inode together and in ascending order.  This improves
performance when reading those nodes especially when bulk-read
is used.

Signed-off-by: Adrian Hunter <ext-adrian.hunter@nokia.com>
This commit is contained in:
Adrian Hunter 2008-09-11 12:57:49 +03:00 committed by Artem Bityutskiy
parent bed79935de
commit 46773be497
1 changed files with 72 additions and 10 deletions
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82
fs/ubifs/gc.c
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@ -95,6 +95,48 @@ static int switch_gc_head(struct ubifs_info *c)
return err;
}
/**
* joinup - bring data nodes for an inode together.
* @c: UBIFS file-system description object
* @sleb: describes scanned LEB
* @inum: inode number
* @blk: block number
* @data: list to which to add data nodes
*
* This function looks at the first few nodes in the scanned LEB @sleb and adds
* them to @data if they are data nodes from @inum and have a larger block
* number than @blk. This function returns %0 on success and a negative error
* code on failure.
*/
static int joinup(struct ubifs_info *c, struct ubifs_scan_leb *sleb, ino_t inum,
unsigned int blk, struct list_head *data)
{
int err, cnt = 6, lnum = sleb->lnum, offs;
struct ubifs_scan_node *snod, *tmp;
union ubifs_key *key;
list_for_each_entry_safe(snod, tmp, &sleb->nodes, list) {
key = &snod->key;
if (key_inum(c, key) == inum &&
key_type(c, key) == UBIFS_DATA_KEY &&
key_block(c, key) > blk) {
offs = snod->offs;
err = ubifs_tnc_has_node(c, key, 0, lnum, offs, 0);
if (err < 0)
return err;
list_del(&snod->list);
if (err) {
list_add_tail(&snod->list, data);
blk = key_block(c, key);
} else
kfree(snod);
cnt = 6;
} else if (--cnt == 0)
break;
}
return 0;
}
/**
* move_nodes - move nodes.
* @c: UBIFS file-system description object
@ -116,16 +158,21 @@ static int switch_gc_head(struct ubifs_info *c)
static int move_nodes(struct ubifs_info *c, struct ubifs_scan_leb *sleb)
{
struct ubifs_scan_node *snod, *tmp;
struct list_head large, medium, small;
struct list_head data, large, medium, small;
struct ubifs_wbuf *wbuf = &c->jheads[GCHD].wbuf;
int avail, err, min = INT_MAX;
unsigned int blk = 0;
ino_t inum = 0;
INIT_LIST_HEAD(&data);
INIT_LIST_HEAD(&large);
INIT_LIST_HEAD(&medium);
INIT_LIST_HEAD(&small);
list_for_each_entry_safe(snod, tmp, &sleb->nodes, list) {
struct list_head *lst;
while (!list_empty(&sleb->nodes)) {
struct list_head *lst = sleb->nodes.next;
snod = list_entry(lst, struct ubifs_scan_node, list);
ubifs_assert(snod->type != UBIFS_IDX_NODE);
ubifs_assert(snod->type != UBIFS_REF_NODE);
@ -136,7 +183,6 @@ static int move_nodes(struct ubifs_info *c, struct ubifs_scan_leb *sleb)
if (err < 0)
goto out;
lst = &snod->list;
list_del(lst);
if (!err) {
/* The node is obsolete, remove it from the list */
@ -145,15 +191,30 @@ static int move_nodes(struct ubifs_info *c, struct ubifs_scan_leb *sleb)
}
/*
* Sort the list of nodes so that large nodes go first, and
* small nodes go last.
* Sort the list of nodes so that data nodes go first, large
* nodes go second, and small nodes go last.
*/
if (snod->len > MEDIUM_NODE_WM)
list_add(lst, &large);
if (key_type(c, &snod->key) == UBIFS_DATA_KEY) {
if (inum != key_inum(c, &snod->key)) {
if (inum) {
/*
* Try to move data nodes from the same
* inode together.
*/
err = joinup(c, sleb, inum, blk, &data);
if (err)
goto out;
}
inum = key_inum(c, &snod->key);
blk = key_block(c, &snod->key);
}
list_add_tail(lst, &data);
} else if (snod->len > MEDIUM_NODE_WM)
list_add_tail(lst, &large);
else if (snod->len > SMALL_NODE_WM)
list_add(lst, &medium);
list_add_tail(lst, &medium);
else
list_add(lst, &small);
list_add_tail(lst, &small);
/* And find the smallest node */
if (snod->len < min)
@ -164,6 +225,7 @@ static int move_nodes(struct ubifs_info *c, struct ubifs_scan_leb *sleb)
* Join the tree lists so that we'd have one roughly sorted list
* ('large' will be the head of the joined list).
*/
list_splice(&data, &large);
list_splice(&medium, large.prev);
list_splice(&small, large.prev);