Patchwork [4/4] ext4: Speed up FITRIM by recording flags in ext4_group_info.

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Submitter Tao Ma
Date Feb. 9, 2011, 5:57 a.m.
Message ID <1297231048-3458-4-git-send-email-tm@tao.ma>
Download mbox | patch
Permalink /patch/82432/
State Superseded
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Comments

Tao Ma - Feb. 9, 2011, 5:57 a.m.
From: Tao Ma <boyu.mt@taobao.com>

In ext4, when FITRIM is called every time, we iterate all the
groups and do trim one by one. It is a bit time wasting if the
group has been trimmed and there is no change since the last
trim.

So this patch adds a new flag in ext4_group_info->bb_state to
indicate that the group has been trimmed, and it will be cleared
if some blocks is freed(in release_blocks_on_commit). Another
trim_minlen is added in ext4_sb_info to record the last minlen
we use to trim the volume, so that if the caller provide a small
one, we will go on the trim regardless of the bb_state. The idea
is inspired by Andreas  and Lukas Czerner.

Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: Lukas Czerner <lczerner@redhat.com>
Signed-off-by: Tao Ma <boyu.mt@taobao.com>
---
 fs/ext4/ext4.h    |    8 +++++++-
 fs/ext4/mballoc.c |   22 ++++++++++++++++++++++
 2 files changed, 29 insertions(+), 1 deletions(-)
Lukas Czerner - Feb. 9, 2011, 2:01 p.m.
On Wed, 9 Feb 2011, Tao Ma wrote:

> From: Tao Ma <boyu.mt@taobao.com>
> 
> In ext4, when FITRIM is called every time, we iterate all the
> groups and do trim one by one. It is a bit time wasting if the
> group has been trimmed and there is no change since the last
> trim.
> 
> So this patch adds a new flag in ext4_group_info->bb_state to
> indicate that the group has been trimmed, and it will be cleared
> if some blocks is freed(in release_blocks_on_commit). Another
> trim_minlen is added in ext4_sb_info to record the last minlen
> we use to trim the volume, so that if the caller provide a small
> one, we will go on the trim regardless of the bb_state. The idea
> is inspired by Andreas  and Lukas Czerner.

Hi Tao,

This is great, thanks for the patch! Do you have any benchmark numbers
showing how much does it improve FSTRIM time ? It seems it might help a
lot. Couple of comments bellow.

> 
> Cc: Andreas Dilger <adilger.kernel@dilger.ca>
> Cc: Lukas Czerner <lczerner@redhat.com>
> Signed-off-by: Tao Ma <boyu.mt@taobao.com>
> ---
>  fs/ext4/ext4.h    |    8 +++++++-
>  fs/ext4/mballoc.c |   22 ++++++++++++++++++++++
>  2 files changed, 29 insertions(+), 1 deletions(-)
> 
> diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
> index 0c8d97b..684f48e 100644
> --- a/fs/ext4/ext4.h
> +++ b/fs/ext4/ext4.h
> @@ -1200,6 +1200,9 @@ struct ext4_sb_info {
>  	struct ext4_li_request *s_li_request;
>  	/* Wait multiplier for lazy initialization thread */
>  	unsigned int s_li_wait_mult;
> +
> +	/* record the last minlen when FITRIM is called. */
> +	u64 trim_minlen;

Maybe this is a bit nitpicking, but it is not very clear what is the
"trim_minlen" for. I would rather use something like
"last_trim_minblks", or similar.

>  };
>  
>  static inline struct ext4_sb_info *EXT4_SB(struct super_block *sb)
> @@ -1970,10 +1973,13 @@ struct ext4_group_info {
>  					 * 5 free 8-block regions. */
>  };
>  
> -#define EXT4_GROUP_INFO_NEED_INIT_BIT	0
> +#define EXT4_GROUP_INFO_NEED_INIT_BIT		0
> +#define EXT4_GROUP_INFO_HAS_BEEN_TRIMMED	1
>  
>  #define EXT4_MB_GRP_NEED_INIT(grp)	\
>  	(test_bit(EXT4_GROUP_INFO_NEED_INIT_BIT, &((grp)->bb_state)))
> +#define EXT4_MB_GRP_HAS_BEEN_TRIMMED(grp)	\
> +	(test_bit(EXT4_GROUP_INFO_HAS_BEEN_TRIMMED, &((grp)->bb_state)))
>  
>  #define EXT4_MAX_CONTENTION		8
>  #define EXT4_CONTENTION_THRESHOLD	2
> diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
> index 4eadac8..3f6b809 100644
> --- a/fs/ext4/mballoc.c
> +++ b/fs/ext4/mballoc.c
> @@ -1563,6 +1563,9 @@ static int mb_mark_used(struct ext4_buddy *e4b, struct ext4_free_extent *ex)
>  	mb_set_bits(EXT4_MB_BITMAP(e4b), ex->fe_start, len0);
>  	mb_check_buddy(e4b);
>  
> +	if (!ret)
> +		EXT4_SB(sb)->trim_minlen = minlen;
> +

Did you even tried to compile it ? "minlen" is not defined in
mb_mark_used(), also it does make sense to set trim_minlen there. Did
not you meant it to be in ext4_trim_fs ?

>  	return ret;
>  }
>  
> @@ -2687,6 +2690,16 @@ static void release_blocks_on_commit(journal_t *journal, transaction_t *txn)
>  		rb_erase(&entry->node, &(db->bb_free_root));
>  		mb_free_blocks(NULL, &e4b, entry->start_blk, entry->count);
>  
> +		/*
> +		 * Clear the trimmed flag for the group so that the next
> +		 * ext4_trim_fs can trim it.
> +		 * If the volume is mounted with -o discard, online discard
> +		 * is supported and the free blocks will be trimmed online.
> +		 */
> +		if (!test_opt(sb, DISCARD))
> +			clear_bit(EXT4_GROUP_INFO_HAS_BEEN_TRIMMED,
> +				  &(db->bb_state));
> +
>  		if (!db->bb_free_root.rb_node) {
>  			/* No more items in the per group rb tree
>  			 * balance refcounts from ext4_mb_free_metadata()
> @@ -4772,6 +4785,10 @@ ext4_grpblk_t ext4_trim_all_free(struct super_block *sb, struct ext4_buddy *e4b,
>  
>  	ext4_lock_group(sb, group);
>  
> +	if (EXT4_MB_GRP_HAS_BEEN_TRIMMED(e4b->bd_info) &&
> +	    minblocks >= EXT4_SB(sb)->trim_minlen)
> +		goto out;
> +

I think this can be placed in the ext4_trim_fs() in the for() loop so we can
avoid unnecessary call to ext4_trim_all_free.

>  	trace_ext4_trim_all_free(sb, group, start, max);
>  
>  	while (start < max) {
> @@ -4804,6 +4821,11 @@ ext4_grpblk_t ext4_trim_all_free(struct super_block *sb, struct ext4_buddy *e4b,
>  		if ((e4b->bd_info->bb_free - free_count) < minblocks)
>  			break;
>  	}
> +
> +	if (!ret)
> +		set_bit(EXT4_GROUP_INFO_HAS_BEEN_TRIMMED,
> +			&(e4b->bd_info->bb_state));
> +out:
>  	ext4_unlock_group(sb, group);
>  
>  	ext4_debug("trimmed %d blocks in the group %d\n",
> 

Thanks!
-Lukas
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Andreas Dilger - Feb. 9, 2011, 7:25 p.m.
On 2011-02-09, at 06:01, Lukas Czerner wrote:
>> @@ -1200,6 +1200,9 @@ struct ext4_sb_info {
>> 	struct ext4_li_request *s_li_request;
>> 	/* Wait multiplier for lazy initialization thread */
>> 	unsigned int s_li_wait_mult;
>> +
>> +	/* record the last minlen when FITRIM is called. */
>> +	u64 trim_minlen;
> 
> Maybe this is a bit nitpicking, but it is not very clear what is the
> "trim_minlen" for. I would rather use something like
> "last_trim_minblks", or similar.

And for good measure, this should use the "s_" prefix to indicate it is in the superblock.

>> +#define EXT4_GROUP_INFO_NEED_INIT_BIT		0
>> +#define EXT4_GROUP_INFO_HAS_BEEN_TRIMMED	1

It would also be good if the names of these fields were consistent, like

+#define EXT4_GROUP_INFO_NEED_INIT_BIT		0
+#define EXT4_GROUP_INFO_WAS_TRIMMED_BIT	1

>> @@ -1563,6 +1563,9 @@ static int mb_mark_used(struct ext4_buddy *e4b, struct ext4_free_extent *ex)
>> 	mb_set_bits(EXT4_MB_BITMAP(e4b), ex->fe_start, len0);
>> 	mb_check_buddy(e4b);
>> 
>> +	if (!ret)
>> +		EXT4_SB(sb)->trim_minlen = minlen;
>> +
> 
> Did you even tried to compile it ? "minlen" is not defined in
> mb_mark_used(), also it does make sense to set trim_minlen there. Did
> not you meant it to be in ext4_trim_fs ?

I was wondering exactly the same thing, but I haven't had time to look at the code.

Cheers, Andreas





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Tao Ma - Feb. 10, 2011, 1:36 a.m.
On 02/09/2011 10:01 PM, Lukas Czerner wrote:
> On Wed, 9 Feb 2011, Tao Ma wrote:
>
>    
>> From: Tao Ma<boyu.mt@taobao.com>
>>
>> In ext4, when FITRIM is called every time, we iterate all the
>> groups and do trim one by one. It is a bit time wasting if the
>> group has been trimmed and there is no change since the last
>> trim.
>>
>> So this patch adds a new flag in ext4_group_info->bb_state to
>> indicate that the group has been trimmed, and it will be cleared
>> if some blocks is freed(in release_blocks_on_commit). Another
>> trim_minlen is added in ext4_sb_info to record the last minlen
>> we use to trim the volume, so that if the caller provide a small
>> one, we will go on the trim regardless of the bb_state. The idea
>> is inspired by Andreas  and Lukas Czerner.
>>      
> Hi Tao,
>
> This is great, thanks for the patch! Do you have any benchmark numbers
> showing how much does it improve FSTRIM time ? It seems it might help a
> lot. Couple of comments bellow.
>    
I have a intel x25m ssd. I will try to collect some data about it and 
update them in the commit log.
>    
>> Cc: Andreas Dilger<adilger.kernel@dilger.ca>
>> Cc: Lukas Czerner<lczerner@redhat.com>
>> Signed-off-by: Tao Ma<boyu.mt@taobao.com>
>> ---
>>   fs/ext4/ext4.h    |    8 +++++++-
>>   fs/ext4/mballoc.c |   22 ++++++++++++++++++++++
>>   2 files changed, 29 insertions(+), 1 deletions(-)
>>
>> diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
>> index 0c8d97b..684f48e 100644
>> --- a/fs/ext4/ext4.h
>> +++ b/fs/ext4/ext4.h
>> @@ -1200,6 +1200,9 @@ struct ext4_sb_info {
>>   	struct ext4_li_request *s_li_request;
>>   	/* Wait multiplier for lazy initialization thread */
>>   	unsigned int s_li_wait_mult;
>> +
>> +	/* record the last minlen when FITRIM is called. */
>> +	u64 trim_minlen;
>>      
> Maybe this is a bit nitpicking, but it is not very clear what is the
> "trim_minlen" for. I would rather use something like
> "last_trim_minblks", or similar.
>    
ok, I will change it in the next round.
>    
>>   };
>>
>>   static inline struct ext4_sb_info *EXT4_SB(struct super_block *sb)
>> @@ -1970,10 +1973,13 @@ struct ext4_group_info {
>>   					 * 5 free 8-block regions. */
>>   };
>>
>> -#define EXT4_GROUP_INFO_NEED_INIT_BIT	0
>> +#define EXT4_GROUP_INFO_NEED_INIT_BIT		0
>> +#define EXT4_GROUP_INFO_HAS_BEEN_TRIMMED	1
>>
>>   #define EXT4_MB_GRP_NEED_INIT(grp)	\
>>   	(test_bit(EXT4_GROUP_INFO_NEED_INIT_BIT,&((grp)->bb_state)))
>> +#define EXT4_MB_GRP_HAS_BEEN_TRIMMED(grp)	\
>> +	(test_bit(EXT4_GROUP_INFO_HAS_BEEN_TRIMMED,&((grp)->bb_state)))
>>
>>   #define EXT4_MAX_CONTENTION		8
>>   #define EXT4_CONTENTION_THRESHOLD	2
>> diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
>> index 4eadac8..3f6b809 100644
>> --- a/fs/ext4/mballoc.c
>> +++ b/fs/ext4/mballoc.c
>> @@ -1563,6 +1563,9 @@ static int mb_mark_used(struct ext4_buddy *e4b, struct ext4_free_extent *ex)
>>   	mb_set_bits(EXT4_MB_BITMAP(e4b), ex->fe_start, len0);
>>   	mb_check_buddy(e4b);
>>
>> +	if (!ret)
>> +		EXT4_SB(sb)->trim_minlen = minlen;
>> +
>>      
> Did you even tried to compile it ? "minlen" is not defined in
> mb_mark_used(), also it does make sense to set trim_minlen there. Did
> not you meant it to be in ext4_trim_fs ?
>    
oh, sorry, this line should be in the function ext4_trim_fs. I just 
rebased my branch to the lastest kernel to see whether it conflicts.
I don't know why they are moved here.  So the right position is:
@@ -4892,6 +4911,9 @@ int ext4_trim_fs(struct super_block *sb, struct 
fstrim_range *range)
         }
         range->len = trimmed * sb->s_blocksize;

+       if (!ret)
+               EXT4_SB(sb)->trim_minlen = minlen;
+
  out:
         return ret;
  }

Sorry for the trouble.
>    
>>   	return ret;
>>   }
>>
>> @@ -2687,6 +2690,16 @@ static void release_blocks_on_commit(journal_t *journal, transaction_t *txn)
>>   		rb_erase(&entry->node,&(db->bb_free_root));
>>   		mb_free_blocks(NULL,&e4b, entry->start_blk, entry->count);
>>
>> +		/*
>> +		 * Clear the trimmed flag for the group so that the next
>> +		 * ext4_trim_fs can trim it.
>> +		 * If the volume is mounted with -o discard, online discard
>> +		 * is supported and the free blocks will be trimmed online.
>> +		 */
>> +		if (!test_opt(sb, DISCARD))
>> +			clear_bit(EXT4_GROUP_INFO_HAS_BEEN_TRIMMED,
>> +				&(db->bb_state));
>> +
>>   		if (!db->bb_free_root.rb_node) {
>>   			/* No more items in the per group rb tree
>>   			 * balance refcounts from ext4_mb_free_metadata()
>> @@ -4772,6 +4785,10 @@ ext4_grpblk_t ext4_trim_all_free(struct super_block *sb, struct ext4_buddy *e4b,
>>
>>   	ext4_lock_group(sb, group);
>>
>> +	if (EXT4_MB_GRP_HAS_BEEN_TRIMMED(e4b->bd_info)&&
>> +	    minblocks>= EXT4_SB(sb)->trim_minlen)
>> +		goto out;
>> +
>>      
> I think this can be placed in the ext4_trim_fs() in the for() loop so we can
> avoid unnecessary call to ext4_trim_all_free.
>    
fair enough. I will update it.

Regards,
Tao
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Tao Ma - Feb. 10, 2011, 1:39 a.m.
On 02/10/2011 03:25 AM, Andreas Dilger wrote:
> On 2011-02-09, at 06:01, Lukas Czerner wrote:
>    
>>> @@ -1200,6 +1200,9 @@ struct ext4_sb_info {
>>> 	struct ext4_li_request *s_li_request;
>>> 	/* Wait multiplier for lazy initialization thread */
>>> 	unsigned int s_li_wait_mult;
>>> +
>>> +	/* record the last minlen when FITRIM is called. */
>>> +	u64 trim_minlen;
>>>        
>> Maybe this is a bit nitpicking, but it is not very clear what is the
>> "trim_minlen" for. I would rather use something like
>> "last_trim_minblks", or similar.
>>      
> And for good measure, this should use the "s_" prefix to indicate it is in the superblock.
>    
ok.
>    
>>> +#define EXT4_GROUP_INFO_NEED_INIT_BIT		0
>>> +#define EXT4_GROUP_INFO_HAS_BEEN_TRIMMED	1
>>>        
> It would also be good if the names of these fields were consistent, like
>
> +#define EXT4_GROUP_INFO_NEED_INIT_BIT		0
> +#define EXT4_GROUP_INFO_WAS_TRIMMED_BIT	1
>    
thanks for the advice.
>    
>>> @@ -1563,6 +1563,9 @@ static int mb_mark_used(struct ext4_buddy *e4b, struct ext4_free_extent *ex)
>>> 	mb_set_bits(EXT4_MB_BITMAP(e4b), ex->fe_start, len0);
>>> 	mb_check_buddy(e4b);
>>>
>>> +	if (!ret)
>>> +		EXT4_SB(sb)->trim_minlen = minlen;
>>> +
>>>        
>> Did you even tried to compile it ? "minlen" is not defined in
>> mb_mark_used(), also it does make sense to set trim_minlen there. Did
>> not you meant it to be in ext4_trim_fs ?
>>      
> I was wondering exactly the same thing, but I haven't had time to look at the code.
>    
Sorry, it seems to be caused by my rebase. The right place should be in 
the end of ext4_trim_fs.

Regards,
Tao
> Cheers, Andreas
>
>
>
>
>
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>    

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Tao Ma - Feb. 10, 2011, 3:56 a.m.
Hi Lukas,
On 02/09/2011 10:01 PM, Lukas Czerner wrote:
> On Wed, 9 Feb 2011, Tao Ma wrote:
>
>    
>> From: Tao Ma<boyu.mt@taobao.com>
>>
>> In ext4, when FITRIM is called every time, we iterate all the
>> groups and do trim one by one. It is a bit time wasting if the
>> group has been trimmed and there is no change since the last
>> trim.
>>
>> So this patch adds a new flag in ext4_group_info->bb_state to
>> indicate that the group has been trimmed, and it will be cleared
>> if some blocks is freed(in release_blocks_on_commit). Another
>> trim_minlen is added in ext4_sb_info to record the last minlen
>> we use to trim the volume, so that if the caller provide a small
>> one, we will go on the trim regardless of the bb_state. The idea
>> is inspired by Andreas  and Lukas Czerner.
>>      
> Hi Tao,
>
> This is great, thanks for the patch! Do you have any benchmark numbers
> showing how much does it improve FSTRIM time ? It seems it might help a
> lot. Couple of comments bellow.
>    
<snip>
>    
>> @@ -4772,6 +4785,10 @@ ext4_grpblk_t ext4_trim_all_free(struct super_block *sb, struct ext4_buddy *e4b,
>>
>>   	ext4_lock_group(sb, group);
>>
>> +	if (EXT4_MB_GRP_HAS_BEEN_TRIMMED(e4b->bd_info)&&
>> +	    minblocks>= EXT4_SB(sb)->trim_minlen)
>> +		goto out;
>> +
>>      
> I think this can be placed in the ext4_trim_fs() in the for() loop so we can
> avoid unnecessary call to ext4_trim_all_free.
>    
I remembered why I put the check here. We have to check this flag with 
the group locked. So in ext4_trim_fs, we don't lock the group and it is 
unsafe to check it there since we may free some blocks and clear the bit 
in the same time in release_blocks_on_commit.

Regards,
Tao
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Patch

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 0c8d97b..684f48e 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -1200,6 +1200,9 @@  struct ext4_sb_info {
 	struct ext4_li_request *s_li_request;
 	/* Wait multiplier for lazy initialization thread */
 	unsigned int s_li_wait_mult;
+
+	/* record the last minlen when FITRIM is called. */
+	u64 trim_minlen;
 };
 
 static inline struct ext4_sb_info *EXT4_SB(struct super_block *sb)
@@ -1970,10 +1973,13 @@  struct ext4_group_info {
 					 * 5 free 8-block regions. */
 };
 
-#define EXT4_GROUP_INFO_NEED_INIT_BIT	0
+#define EXT4_GROUP_INFO_NEED_INIT_BIT		0
+#define EXT4_GROUP_INFO_HAS_BEEN_TRIMMED	1
 
 #define EXT4_MB_GRP_NEED_INIT(grp)	\
 	(test_bit(EXT4_GROUP_INFO_NEED_INIT_BIT, &((grp)->bb_state)))
+#define EXT4_MB_GRP_HAS_BEEN_TRIMMED(grp)	\
+	(test_bit(EXT4_GROUP_INFO_HAS_BEEN_TRIMMED, &((grp)->bb_state)))
 
 #define EXT4_MAX_CONTENTION		8
 #define EXT4_CONTENTION_THRESHOLD	2
diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index 4eadac8..3f6b809 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -1563,6 +1563,9 @@  static int mb_mark_used(struct ext4_buddy *e4b, struct ext4_free_extent *ex)
 	mb_set_bits(EXT4_MB_BITMAP(e4b), ex->fe_start, len0);
 	mb_check_buddy(e4b);
 
+	if (!ret)
+		EXT4_SB(sb)->trim_minlen = minlen;
+
 	return ret;
 }
 
@@ -2687,6 +2690,16 @@  static void release_blocks_on_commit(journal_t *journal, transaction_t *txn)
 		rb_erase(&entry->node, &(db->bb_free_root));
 		mb_free_blocks(NULL, &e4b, entry->start_blk, entry->count);
 
+		/*
+		 * Clear the trimmed flag for the group so that the next
+		 * ext4_trim_fs can trim it.
+		 * If the volume is mounted with -o discard, online discard
+		 * is supported and the free blocks will be trimmed online.
+		 */
+		if (!test_opt(sb, DISCARD))
+			clear_bit(EXT4_GROUP_INFO_HAS_BEEN_TRIMMED,
+				  &(db->bb_state));
+
 		if (!db->bb_free_root.rb_node) {
 			/* No more items in the per group rb tree
 			 * balance refcounts from ext4_mb_free_metadata()
@@ -4772,6 +4785,10 @@  ext4_grpblk_t ext4_trim_all_free(struct super_block *sb, struct ext4_buddy *e4b,
 
 	ext4_lock_group(sb, group);
 
+	if (EXT4_MB_GRP_HAS_BEEN_TRIMMED(e4b->bd_info) &&
+	    minblocks >= EXT4_SB(sb)->trim_minlen)
+		goto out;
+
 	trace_ext4_trim_all_free(sb, group, start, max);
 
 	while (start < max) {
@@ -4804,6 +4821,11 @@  ext4_grpblk_t ext4_trim_all_free(struct super_block *sb, struct ext4_buddy *e4b,
 		if ((e4b->bd_info->bb_free - free_count) < minblocks)
 			break;
 	}
+
+	if (!ret)
+		set_bit(EXT4_GROUP_INFO_HAS_BEEN_TRIMMED,
+			&(e4b->bd_info->bb_state));
+out:
 	ext4_unlock_group(sb, group);
 
 	ext4_debug("trimmed %d blocks in the group %d\n",