2022-06-06 16:07:03

by hanjinke

[permalink] [raw]
Subject: [PATCH] ext4: reuse order and buddy in mb_mark_used when buddy split

From: hanjinke <[email protected]>

After each buddy split, mb_mark_used will search the proper order
for the block which may consume some loop in mb_find_order_for_block.
In fact, we can reuse the oder and buddy generated by the buddy split.

Reviewed by: [email protected]
Signed-off-by: hanjinke <[email protected]>
---
fs/ext4/mballoc.c | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index 9f12f29bc346..c7ac6b269dd8 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -1933,6 +1933,7 @@ static int mb_mark_used(struct ext4_buddy *e4b, struct ext4_free_extent *ex)
unsigned ret = 0;
int len0 = len;
void *buddy;
+ bool split = false;

BUG_ON(start + len > (e4b->bd_sb->s_blocksize << 3));
BUG_ON(e4b->bd_group != ex->fe_group);
@@ -1957,12 +1958,16 @@ static int mb_mark_used(struct ext4_buddy *e4b, struct ext4_free_extent *ex)

/* let's maintain buddy itself */
while (len) {
- ord = mb_find_order_for_block(e4b, start);
+ if (!split)
+ ord = mb_find_order_for_block(e4b, start);

if (((start >> ord) << ord) == start && len >= (1 << ord)) {
/* the whole chunk may be allocated at once! */
mlen = 1 << ord;
- buddy = mb_find_buddy(e4b, ord, &max);
+ if (!split)
+ buddy = mb_find_buddy(e4b, ord, &max);
+ else
+ split = false;
BUG_ON((start >> ord) >= max);
mb_set_bit(start >> ord, buddy);
e4b->bd_info->bb_counters[ord]--;
@@ -1989,6 +1994,7 @@ static int mb_mark_used(struct ext4_buddy *e4b, struct ext4_free_extent *ex)
mb_clear_bit(cur + 1, buddy);
e4b->bd_info->bb_counters[ord]++;
e4b->bd_info->bb_counters[ord]++;
+ split = true;
}
mb_set_largest_free_order(e4b->bd_sb, e4b->bd_info);

--
2.20.1


2022-06-21 02:43:59

by hanjinke

[permalink] [raw]
Subject: Re: [PATCH] ext4: reuse order and buddy in mb_mark_used when buddy split

hi, friendly pinging...

在 2022/6/6 下午11:53, Jinke Han 写道:
> From: hanjinke <[email protected]>
>
> After each buddy split, mb_mark_used will search the proper order
> for the block which may consume some loop in mb_find_order_for_block.
> In fact, we can reuse the oder and buddy generated by the buddy split.
>
> Reviewed by: [email protected]
> Signed-off-by: hanjinke <[email protected]>
> ---
> fs/ext4/mballoc.c | 10 ++++++++--
> 1 file changed, 8 insertions(+), 2 deletions(-)
>
> diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
> index 9f12f29bc346..c7ac6b269dd8 100644
> --- a/fs/ext4/mballoc.c
> +++ b/fs/ext4/mballoc.c
> @@ -1933,6 +1933,7 @@ static int mb_mark_used(struct ext4_buddy *e4b, struct ext4_free_extent *ex)
> unsigned ret = 0;
> int len0 = len;
> void *buddy;
> + bool split = false;
>
> BUG_ON(start + len > (e4b->bd_sb->s_blocksize << 3));
> BUG_ON(e4b->bd_group != ex->fe_group);
> @@ -1957,12 +1958,16 @@ static int mb_mark_used(struct ext4_buddy *e4b, struct ext4_free_extent *ex)
>
> /* let's maintain buddy itself */
> while (len) {
> - ord = mb_find_order_for_block(e4b, start);
> + if (!split)
> + ord = mb_find_order_for_block(e4b, start);
>
> if (((start >> ord) << ord) == start && len >= (1 << ord)) {
> /* the whole chunk may be allocated at once! */
> mlen = 1 << ord;
> - buddy = mb_find_buddy(e4b, ord, &max);
> + if (!split)
> + buddy = mb_find_buddy(e4b, ord, &max);
> + else
> + split = false;
> BUG_ON((start >> ord) >= max);
> mb_set_bit(start >> ord, buddy);
> e4b->bd_info->bb_counters[ord]--;
> @@ -1989,6 +1994,7 @@ static int mb_mark_used(struct ext4_buddy *e4b, struct ext4_free_extent *ex)
> mb_clear_bit(cur + 1, buddy);
> e4b->bd_info->bb_counters[ord]++;
> e4b->bd_info->bb_counters[ord]++;
> + split = true;
> }
> mb_set_largest_free_order(e4b->bd_sb, e4b->bd_info);
>