jffs2: Dynamically choose inocache hash size

When JFFS2 is used for large volumes, the mount times are quite long. Increasing the hash size provides a significant speed boost on the OLPC XO-1 laptop. Add logic that dynamically selects a hash size based on the size of the medium. A 64mb medium will result in a hash size of 128, and a 512mb medium will result in a hash size of 1024. Signed-off-by: Daniel Drake <dsd@laptop.org> Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

jffs2: Dynamically choose inocache hash size
When JFFS2 is used for large volumes, the mount times are quite long. Increasing the hash size provides a significant speed boost on the OLPC XO-1 laptop. Add logic that dynamically selects a hash size based on the size of the medium. A 64mb medium will result in a hash size of 128, and a 512mb medium will result in a hash size of 1024. Signed-off-by: Daniel Drake <dsd@laptop.org> Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
Daniel Drake · David Woodhouse
1 parent b46daf7eb1
Showing 5 changed files with 29 additions and 7 deletions Side-by-side Diff
fs/jffs2/build.c
fs/jffs2/fs.c
fs/jffs2/jffs2_fs_sb.h
fs/jffs2/nodelist.c
fs/jffs2/nodelist.h
@@ -23,7 +23,7 @@
 static inline struct jffs2_inode_cache *
 first_inode_chain(int *i, struct jffs2_sb_info *c)
 {
-	for (; *i < INOCACHE_HASHSIZE; (*i)++) {
+	for (; *i < c->inocache_hashsize; (*i)++) {
 		if (c->inocache_list[*i])
 			return c->inocache_list[*i];
 	}
@@ -478,7 +478,26 @@
 	return inode;
 }
  
+static int calculate_inocache_hashsize(uint32_t flash_size)
+{
+	/*
+	 * Pick a inocache hash size based on the size of the medium.
+	 * Count how many megabytes we're dealing with, apply a hashsize twice
+	 * that size, but rounding down to the usual big powers of 2. And keep
+	 * to sensible bounds.
+	 */
  
+	int size_mb = flash_size / 1024 / 1024;
+	int hashsize = (size_mb * 2) & ~0x3f;
+
+	if (hashsize < INOCACHE_HASHSIZE_MIN)
+		return INOCACHE_HASHSIZE_MIN;
+	if (hashsize > INOCACHE_HASHSIZE_MAX)
+		return INOCACHE_HASHSIZE_MAX;
+
+	return hashsize;
+}
+
 int jffs2_do_fill_super(struct super_block *sb, void *data, int silent)
 {
 	struct jffs2_sb_info *c;
@@ -524,7 +543,8 @@
 	if (ret)
 		return ret;
  
-	c->inocache_list = kcalloc(INOCACHE_HASHSIZE, sizeof(struct jffs2_inode_cache *), GFP_KERNEL);
+	c->inocache_hashsize = calculate_inocache_hashsize(c->flash_size);
+	c->inocache_list = kcalloc(c->inocache_hashsize, sizeof(struct jffs2_inode_cache *), GFP_KERNEL);
 	if (!c->inocache_list) {
 		ret = -ENOMEM;
 		goto out_wbuf;
@@ -100,6 +100,7 @@
 	wait_queue_head_t erase_wait;		/* For waiting for erases to complete */
  
 	wait_queue_head_t inocache_wq;
+	int inocache_hashsize;
 	struct jffs2_inode_cache **inocache_list;
 	spinlock_t inocache_lock;
  
@@ -420,7 +420,7 @@
 {
 	struct jffs2_inode_cache *ret;
  
-	ret = c->inocache_list[ino % INOCACHE_HASHSIZE];
+	ret = c->inocache_list[ino % c->inocache_hashsize];
 	while (ret && ret->ino < ino) {
 		ret = ret->next;
 	}
@@ -441,7 +441,7 @@
  
 	dbg_inocache("add %p (ino #%u)\n", new, new->ino);
  
-	prev = &c->inocache_list[new->ino % INOCACHE_HASHSIZE];
+	prev = &c->inocache_list[new->ino % c->inocache_hashsize];
  
 	while ((*prev) && (*prev)->ino < new->ino) {
 		prev = &(*prev)->next;
@@ -462,7 +462,7 @@
 	dbg_inocache("del %p (ino #%u)\n", old, old->ino);
 	spin_lock(&c->inocache_lock);
  
-	prev = &c->inocache_list[old->ino % INOCACHE_HASHSIZE];
+	prev = &c->inocache_list[old->ino % c->inocache_hashsize];
  
 	while ((*prev) && (*prev)->ino < old->ino) {
 		prev = &(*prev)->next;
@@ -487,7 +487,7 @@
 	int i;
 	struct jffs2_inode_cache *this, *next;
  
-	for (i=0; i<INOCACHE_HASHSIZE; i++) {
+	for (i=0; i < c->inocache_hashsize; i++) {
 		this = c->inocache_list[i];
 		while (this) {
 			next = this->next;
@@ -199,7 +199,8 @@
 #define RAWNODE_CLASS_XATTR_DATUM	1
 #define RAWNODE_CLASS_XATTR_REF		2
  
-#define INOCACHE_HASHSIZE 128
+#define INOCACHE_HASHSIZE_MIN 128
+#define INOCACHE_HASHSIZE_MAX 1024
  
 #define write_ofs(c) ((c)->nextblock->offset + (c)->sector_size - (c)->nextblock->free_size)
...	...	@@ -23,7 +23,7 @@
23	23	static inline struct jffs2_inode_cache *
24	24	first_inode_chain(int i, struct jffs2_sb_info c)
25	25	{
26		- for (; i < INOCACHE_HASHSIZE; (i)++) {
	26	+ for (; i < c->inocache_hashsize; (i)++) {
27	27	if (c->inocache_list[*i])
28	28	return c->inocache_list[*i];
29	29	}
...	...	@@ -478,7 +478,26 @@
478	478	return inode;
479	479	}
480	480
	481	+static int calculate_inocache_hashsize(uint32_t flash_size)
	482	+{
	483	+ /*
	484	+ * Pick a inocache hash size based on the size of the medium.
	485	+ * Count how many megabytes we're dealing with, apply a hashsize twice
	486	+ * that size, but rounding down to the usual big powers of 2. And keep
	487	+ * to sensible bounds.
	488	+ */
481	489
	490	+ int size_mb = flash_size / 1024 / 1024;
	491	+ int hashsize = (size_mb * 2) & ~0x3f;
	492	+
	493	+ if (hashsize < INOCACHE_HASHSIZE_MIN)
	494	+ return INOCACHE_HASHSIZE_MIN;
	495	+ if (hashsize > INOCACHE_HASHSIZE_MAX)
	496	+ return INOCACHE_HASHSIZE_MAX;
	497	+
	498	+ return hashsize;
	499	+}
	500	+
482	501	int jffs2_do_fill_super(struct super_block sb, void data, int silent)
483	502	{
484	503	struct jffs2_sb_info *c;
...	...	@@ -524,7 +543,8 @@
524	543	if (ret)
525	544	return ret;
526	545
527		- c->inocache_list = kcalloc(INOCACHE_HASHSIZE, sizeof(struct jffs2_inode_cache *), GFP_KERNEL);
	546	+ c->inocache_hashsize = calculate_inocache_hashsize(c->flash_size);
	547	+ c->inocache_list = kcalloc(c->inocache_hashsize, sizeof(struct jffs2_inode_cache *), GFP_KERNEL);
528	548	if (!c->inocache_list) {
529	549	ret = -ENOMEM;
530	550	goto out_wbuf;
...	...	@@ -100,6 +100,7 @@
100	100	wait_queue_head_t erase_wait; /* For waiting for erases to complete */
101	101
102	102	wait_queue_head_t inocache_wq;
	103	+ int inocache_hashsize;
103	104	struct jffs2_inode_cache **inocache_list;
104	105	spinlock_t inocache_lock;
105	106
...	...	@@ -420,7 +420,7 @@
420	420	{
421	421	struct jffs2_inode_cache *ret;
422	422
423		- ret = c->inocache_list[ino % INOCACHE_HASHSIZE];
	423	+ ret = c->inocache_list[ino % c->inocache_hashsize];
424	424	while (ret && ret->ino < ino) {
425	425	ret = ret->next;
426	426	}
...	...	@@ -441,7 +441,7 @@
441	441
442	442	dbg_inocache("add %p (ino #%u)\n", new, new->ino);
443	443
444		- prev = &c->inocache_list[new->ino % INOCACHE_HASHSIZE];
	444	+ prev = &c->inocache_list[new->ino % c->inocache_hashsize];
445	445
446	446	while ((prev) && (prev)->ino < new->ino) {
447	447	prev = &(*prev)->next;
...	...	@@ -462,7 +462,7 @@
462	462	dbg_inocache("del %p (ino #%u)\n", old, old->ino);
463	463	spin_lock(&c->inocache_lock);
464	464
465		- prev = &c->inocache_list[old->ino % INOCACHE_HASHSIZE];
	465	+ prev = &c->inocache_list[old->ino % c->inocache_hashsize];
466	466
467	467	while ((prev) && (prev)->ino < old->ino) {
468	468	prev = &(*prev)->next;
...	...	@@ -487,7 +487,7 @@
487	487	int i;
488	488	struct jffs2_inode_cache this, next;
489	489
490		- for (i=0; i<INOCACHE_HASHSIZE; i++) {
	490	+ for (i=0; i < c->inocache_hashsize; i++) {
491	491	this = c->inocache_list[i];
492	492	while (this) {
493	493	next = this->next;
...	...	@@ -199,7 +199,8 @@
199	199	#define RAWNODE_CLASS_XATTR_DATUM 1
200	200	#define RAWNODE_CLASS_XATTR_REF 2
201	201
202		-#define INOCACHE_HASHSIZE 128
	202	+#define INOCACHE_HASHSIZE_MIN 128
	203	+#define INOCACHE_HASHSIZE_MAX 1024
203	204
204	205	#define write_ofs(c) ((c)->nextblock->offset + (c)->sector_size - (c)->nextblock->free_size)
205	206