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