[PATCH] drivers/mtd/ubi/wl.c: optimization for in_wl_tree()

[PATCH] drivers/mtd/ubi/wl.c: optimization for in_wl_tree()

[Daniel Santos]

Essentially, instead of performing a search through the tree from the
top down, like we would when doing a lookup, we can just search from the
node up and then check to see if the root of the tree that the node is
in is the same as the one supplied.  Note that if you call this passing
a ubi_wl_entry who's u.rb member has not been inited with rb_init_node()
or added to a tree, the results are undefined.

This should be a little faster, but mostly, it'll be smaller.
---
 drivers/mtd/ubi/wl.c |   32 ++++++++------------------------
 1 files changed, 8 insertions(+), 24 deletions(-)

diff --git a/drivers/mtd/ubi/wl.c b/drivers/mtd/ubi/wl.c
index 9df100a..d415011 100644
--- a/drivers/mtd/ubi/wl.c
+++ b/drivers/mtd/ubi/wl.c
@@ -287,33 +287,17 @@ static int produce_free_peb(struct ubi_device *ubi)
  */
 static int in_wl_tree(struct ubi_wl_entry *e, struct rb_root *root)
 {
-	struct rb_node *p;
-
-	p = root->rb_node;
-	while (p) {
-		struct ubi_wl_entry *e1;
+	struct rb_node *p = &e->u.rb, *parent = rb_parent(&e->u.rb);
 
-		e1 = rb_entry(p, struct ubi_wl_entry, u.rb);
-
-		if (e->pnum == e1->pnum) {
-			ubi_assert(e == e1);
-			return 1;
-		}
+	if (parent == p)
+		return 0;
 
-		if (e->ec < e1->ec)
-			p = p->rb_left;
-		else if (e->ec > e1->ec)
-			p = p->rb_right;
-		else {
-			ubi_assert(e->pnum != e1->pnum);
-			if (e->pnum < e1->pnum)
-				p = p->rb_left;
-			else
-				p = p->rb_right;
-		}
-	}
+	do {
+		p = parent;
+		parent = rb_parent(parent);
+	} while (parent);
 
-	return 0;
+	return p == root->rb_node;
 }
 
 /**
-- 
1.7.3.4

Re: [PATCH] drivers/mtd/ubi/wl.c: optimization for in_wl_tree()

[Daniel Santos]

Oh, and I forgot to mention that I haven't tested it (don't have this
device), but it does compile.

On 06/09/2012 08:57 PM, Daniel Santos wrote:
> Essentially, instead of performing a search through the tree from the
> top down, like we would when doing a lookup, we can just search from the
> node up and then check to see if the root of the tree that the node is
> in is the same as the one supplied.  Note that if you call this passing
> a ubi_wl_entry who's u.rb member has not been inited with rb_init_node()
> or added to a tree, the results are undefined.
>
> This should be a little faster, but mostly, it'll be smaller.
> ---
>  drivers/mtd/ubi/wl.c |   32 ++++++++------------------------
>  1 files changed, 8 insertions(+), 24 deletions(-)
>
> diff --git a/drivers/mtd/ubi/wl.c b/drivers/mtd/ubi/wl.c
> index 9df100a..d415011 100644
> --- a/drivers/mtd/ubi/wl.c
> +++ b/drivers/mtd/ubi/wl.c
> @@ -287,33 +287,17 @@ static int produce_free_peb(struct ubi_device *ubi)
>   */
>  static int in_wl_tree(struct ubi_wl_entry *e, struct rb_root *root)
>  {
> -	struct rb_node *p;
> -
> -	p = root->rb_node;
> -	while (p) {
> -		struct ubi_wl_entry *e1;
> +	struct rb_node *p = &e->u.rb, *parent = rb_parent(&e->u.rb);
>  
> -		e1 = rb_entry(p, struct ubi_wl_entry, u.rb);
> -
> -		if (e->pnum == e1->pnum) {
> -			ubi_assert(e == e1);
> -			return 1;
> -		}
> +	if (parent == p)
> +		return 0;
>  
> -		if (e->ec < e1->ec)
> -			p = p->rb_left;
> -		else if (e->ec > e1->ec)
> -			p = p->rb_right;
> -		else {
> -			ubi_assert(e->pnum != e1->pnum);
> -			if (e->pnum < e1->pnum)
> -				p = p->rb_left;
> -			else
> -				p = p->rb_right;
> -		}
> -	}
> +	do {
> +		p = parent;
> +		parent = rb_parent(parent);
> +	} while (parent);
>  
> -	return 0;
> +	return p == root->rb_node;
>  }
>  
>  /**

-- 
Daniel

"Just because you go to church on Sunday, it doesn't absolve you from
where you put your dick during the week" -- Michele Q.

Re: [PATCH] drivers/mtd/ubi/wl.c: optimization for in_wl_tree()

[Richard Weinberger]

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Am 10.06.2012 04:02, schrieb Daniel Santos:
> Oh, and I forgot to mention that I haven't tested it (don't have this
> device), but it does compile.

Sure you have this device. :-)

modprobe nandsim
modprobe ubi mtd=0
ubimkvol /dev/ubi0 -n 0 -N test -m
mkfs.ubifs /dev/ubi0_0
mount -t ubifs /dev/ubi0_0 /mnt/ubifs
testing....
umount /mnt/ubifs

Thanks,
//richard

P.s: Please send use get_maintainer.pl.


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