Patchwork ext4: try fast merge operation in ext4_mb_free_metadata()

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Submitter jing zhang
Date March 24, 2010, 1:32 p.m.
Message ID <ac8f92701003240632t2bcdb0b4l1d7543e3b1ffc9e7@mail.gmail.com>
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Permalink /patch/48413/
State New
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jing zhang - March 24, 2010, 1:32 p.m.
From: Jing Zhang <zj.barak@gmail.com>

Date: Wed Mar 24 21:30:22     2010

There may exist fast path for merge if merge-able.

Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Andreas Dilger <adilger@sun.com>
Cc: Dave Kleikamp <shaggy@linux.vnet.ibm.com>
Signed-off-by: Jing Zhang <zj.barak@gmail.com>

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Aneesh Kumar K.V - March 24, 2010, 5:04 p.m.
On Wed, 24 Mar 2010 21:32:39 +0800, jing zhang <zj.barak@gmail.com> wrote:
> From: Jing Zhang <zj.barak@gmail.com>
> 
> Date: Wed Mar 24 21:30:22     2010
> 
> There may exist fast path for merge if merge-able.
> 
> Cc: Theodore Ts'o <tytso@mit.edu>
> Cc: Andreas Dilger <adilger@sun.com>
> Cc: Dave Kleikamp <shaggy@linux.vnet.ibm.com>
> Signed-off-by: Jing Zhang <zj.barak@gmail.com>
> 
> ---
> 
> --- linux-2.6.32/fs/ext4/mballoc.c	2009-12-03 11:51:22.000000000 +0800
> +++ ext4_mm_leak/mballoc7.c	2010-03-24 21:27:24.000000000 +0800
> @@ -4385,6 +4385,24 @@ ext4_mb_free_metadata(handle_t *handle,
>  		}
>  	}
> 
> +	if (parent) {
> +		/* let's try fast path */
> +		entry = rb_entry(parent, struct ext4_free_data, node);
> +		if (n == &parent->rb_left) {
> +			if (can_merge(new_entry, entry)) {
> +				entry->start_blk = new_entry->start_blk;
> +				entry->count += new_entry->count;
> +				/* and info the caller that new_entry is
> +				 * not used yet.
> +				 */
> +				return 0;

return 0 on success so you may want -1 here 

> +			}
> +		}
> +		else if (can_merge(entry, new_entry)) {
> +			entry->count += new_entry->count;
> +			return 0;
> +		}
> +	}
>  	rb_link_node(new_node, parent, n);
>  	rb_insert_color(new_node, &db->bb_free_root);
> --

-aneesh
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jing zhang - March 25, 2010, 2:11 p.m.
2010/3/25, Aneesh Kumar K. V <aneesh.kumar@linux.vnet.ibm.com>:
> On Wed, 24 Mar 2010 21:32:39 +0800, jing zhang <zj.barak@gmail.com> wrote:
>> From: Jing Zhang <zj.barak@gmail.com>
>>
>> Date: Wed Mar 24 21:30:22     2010
>>
>> There may exist fast path for merge if merge-able.
>>
>> Cc: Theodore Ts'o <tytso@mit.edu>
>> Cc: Andreas Dilger <adilger@sun.com>
>> Cc: Dave Kleikamp <shaggy@linux.vnet.ibm.com>
>> Signed-off-by: Jing Zhang <zj.barak@gmail.com>
>>
>> ---
>>
>> --- linux-2.6.32/fs/ext4/mballoc.c	2009-12-03 11:51:22.000000000 +0800
>> +++ ext4_mm_leak/mballoc7.c	2010-03-24 21:27:24.000000000 +0800
>> @@ -4385,6 +4385,24 @@ ext4_mb_free_metadata(handle_t *handle,
>>  		}
>>  	}
>>
>> +	if (parent) {
>> +		/* let's try fast path */
>> +		entry = rb_entry(parent, struct ext4_free_data, node);
>> +		if (n == &parent->rb_left) {
>> +			if (can_merge(new_entry, entry)) {
>> +				entry->start_blk = new_entry->start_blk;
>> +				entry->count += new_entry->count;
>> +				/* and info the caller that new_entry is
>> +				 * not used yet.
>> +				 */
>> +				return 0;
>
> return 0 on success so you may want -1 here

Agree.

      - zj

>
>> +			}
>> +		}
>> +		else if (can_merge(entry, new_entry)) {
>> +			entry->count += new_entry->count;
>> +			return 0;
>> +		}
>> +	}
>>  	rb_link_node(new_node, parent, n);
>>  	rb_insert_color(new_node, &db->bb_free_root);
>> --
>
> -aneesh
>
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Patch

--- linux-2.6.32/fs/ext4/mballoc.c	2009-12-03 11:51:22.000000000 +0800
+++ ext4_mm_leak/mballoc7.c	2010-03-24 21:27:24.000000000 +0800
@@ -4385,6 +4385,24 @@  ext4_mb_free_metadata(handle_t *handle,
 		}
 	}

+	if (parent) {
+		/* let's try fast path */
+		entry = rb_entry(parent, struct ext4_free_data, node);
+		if (n == &parent->rb_left) {
+			if (can_merge(new_entry, entry)) {
+				entry->start_blk = new_entry->start_blk;
+				entry->count += new_entry->count;
+				/* and info the caller that new_entry is
+				 * not used yet.
+				 */
+				return 0;
+			}
+		}
+		else if (can_merge(entry, new_entry)) {
+			entry->count += new_entry->count;
+			return 0;
+		}
+	}
 	rb_link_node(new_node, parent, n);
 	rb_insert_color(new_node, &db->bb_free_root);
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