As Yanming reported in bugzilla:
https://bugzilla.kernel.org/show_bug.cgi?id=215914
The root cause is: in a very small sized image, it's very easy to
exceed threshold of foreground GC, if we calculate free space and
dirty data based on section granularity, in corner case,
has_not_enough_free_secs() will always return true, result in
deadloop in f2fs_gc().
So this patch refactors has_not_enough_free_secs() as below to fix
this issue:
1. calculate needed space based on block granularity, and separate
all blocks to two parts, section part, and block part, comparing
section part to free section, and comparing block part to free space
in openned log.
2. account F2FS_DIRTY_NODES, F2FS_DIRTY_IMETA and F2FS_DIRTY_DENTS
as node block consumer;
3. account F2FS_DIRTY_DENTS as data block consumer;
Cc: [email protected]
Reported-by: Ming Yan <[email protected]>
Signed-off-by: Chao Yu <[email protected]>
---
fs/f2fs/segment.h | 30 +++++++++++++++++-------------
1 file changed, 17 insertions(+), 13 deletions(-)
diff --git a/fs/f2fs/segment.h b/fs/f2fs/segment.h
index 8a591455d796..28f7aa9b40bf 100644
--- a/fs/f2fs/segment.h
+++ b/fs/f2fs/segment.h
@@ -575,11 +575,10 @@ static inline int reserved_sections(struct f2fs_sb_info *sbi)
return GET_SEC_FROM_SEG(sbi, reserved_segments(sbi));
}
-static inline bool has_curseg_enough_space(struct f2fs_sb_info *sbi)
+static inline bool has_curseg_enough_space(struct f2fs_sb_info *sbi,
+ unsigned int node_blocks, unsigned int dent_blocks)
{
- unsigned int node_blocks = get_pages(sbi, F2FS_DIRTY_NODES) +
- get_pages(sbi, F2FS_DIRTY_DENTS);
- unsigned int dent_blocks = get_pages(sbi, F2FS_DIRTY_DENTS);
+
unsigned int segno, left_blocks;
int i;
@@ -605,19 +604,24 @@ static inline bool has_curseg_enough_space(struct f2fs_sb_info *sbi)
static inline bool has_not_enough_free_secs(struct f2fs_sb_info *sbi,
int freed, int needed)
{
- int node_secs = get_blocktype_secs(sbi, F2FS_DIRTY_NODES);
- int dent_secs = get_blocktype_secs(sbi, F2FS_DIRTY_DENTS);
- int imeta_secs = get_blocktype_secs(sbi, F2FS_DIRTY_IMETA);
+ unsigned int total_node_blocks = get_pages(sbi, F2FS_DIRTY_NODES) +
+ get_pages(sbi, F2FS_DIRTY_DENTS) +
+ get_pages(sbi, F2FS_DIRTY_IMETA);
+ unsigned int total_dent_blocks = get_pages(sbi, F2FS_DIRTY_DENTS);
+ unsigned int node_secs = total_node_blocks / BLKS_PER_SEC(sbi);
+ unsigned int dent_secs = total_dent_blocks / BLKS_PER_SEC(sbi);
+ unsigned int node_blocks = total_node_blocks % BLKS_PER_SEC(sbi);
+ unsigned int dent_blocks = total_dent_blocks % BLKS_PER_SEC(sbi);
if (unlikely(is_sbi_flag_set(sbi, SBI_POR_DOING)))
return false;
- if (free_sections(sbi) + freed == reserved_sections(sbi) + needed &&
- has_curseg_enough_space(sbi))
- return false;
- return (free_sections(sbi) + freed) <=
- (node_secs + 2 * dent_secs + imeta_secs +
- reserved_sections(sbi) + needed);
+ if (free_sections(sbi) + freed <=
+ node_secs + dent_secs + reserved_sections(sbi) + needed)
+ return true;
+ if (!has_curseg_enough_space(sbi, node_blocks, dent_blocks))
+ return true;
+ return false;
}
static inline bool f2fs_is_checkpoint_ready(struct f2fs_sb_info *sbi)
--
2.32.0
On 2022/5/4 6:25, Jaegeuk Kim wrote:
> On 04/30, Chao Yu wrote:
>> As Yanming reported in bugzilla:
>>
>> https://bugzilla.kernel.org/show_bug.cgi?id=215914
>>
>> The root cause is: in a very small sized image, it's very easy to
>> exceed threshold of foreground GC, if we calculate free space and
>> dirty data based on section granularity, in corner case,
>> has_not_enough_free_secs() will always return true, result in
>> deadloop in f2fs_gc().
>
> Performance regression was reported. Can we check this for very small sized
> image only?
I noticed that, I've fixed the issue in v2, could you please take a look?
Thanks,
>
>>
>> So this patch refactors has_not_enough_free_secs() as below to fix
>> this issue:
>> 1. calculate needed space based on block granularity, and separate
>> all blocks to two parts, section part, and block part, comparing
>> section part to free section, and comparing block part to free space
>> in openned log.
>> 2. account F2FS_DIRTY_NODES, F2FS_DIRTY_IMETA and F2FS_DIRTY_DENTS
>> as node block consumer;
>> 3. account F2FS_DIRTY_DENTS as data block consumer;
>>
>> Cc: [email protected]
>> Reported-by: Ming Yan <[email protected]>
>> Signed-off-by: Chao Yu <[email protected]>
>> ---
>> fs/f2fs/segment.h | 30 +++++++++++++++++-------------
>> 1 file changed, 17 insertions(+), 13 deletions(-)
>>
>> diff --git a/fs/f2fs/segment.h b/fs/f2fs/segment.h
>> index 8a591455d796..28f7aa9b40bf 100644
>> --- a/fs/f2fs/segment.h
>> +++ b/fs/f2fs/segment.h
>> @@ -575,11 +575,10 @@ static inline int reserved_sections(struct f2fs_sb_info *sbi)
>> return GET_SEC_FROM_SEG(sbi, reserved_segments(sbi));
>> }
>>
>> -static inline bool has_curseg_enough_space(struct f2fs_sb_info *sbi)
>> +static inline bool has_curseg_enough_space(struct f2fs_sb_info *sbi,
>> + unsigned int node_blocks, unsigned int dent_blocks)
>> {
>> - unsigned int node_blocks = get_pages(sbi, F2FS_DIRTY_NODES) +
>> - get_pages(sbi, F2FS_DIRTY_DENTS);
>> - unsigned int dent_blocks = get_pages(sbi, F2FS_DIRTY_DENTS);
>> +
>> unsigned int segno, left_blocks;
>> int i;
>>
>> @@ -605,19 +604,24 @@ static inline bool has_curseg_enough_space(struct f2fs_sb_info *sbi)
>> static inline bool has_not_enough_free_secs(struct f2fs_sb_info *sbi,
>> int freed, int needed)
>> {
>> - int node_secs = get_blocktype_secs(sbi, F2FS_DIRTY_NODES);
>> - int dent_secs = get_blocktype_secs(sbi, F2FS_DIRTY_DENTS);
>> - int imeta_secs = get_blocktype_secs(sbi, F2FS_DIRTY_IMETA);
>> + unsigned int total_node_blocks = get_pages(sbi, F2FS_DIRTY_NODES) +
>> + get_pages(sbi, F2FS_DIRTY_DENTS) +
>> + get_pages(sbi, F2FS_DIRTY_IMETA);
>> + unsigned int total_dent_blocks = get_pages(sbi, F2FS_DIRTY_DENTS);
>> + unsigned int node_secs = total_node_blocks / BLKS_PER_SEC(sbi);
>> + unsigned int dent_secs = total_dent_blocks / BLKS_PER_SEC(sbi);
>> + unsigned int node_blocks = total_node_blocks % BLKS_PER_SEC(sbi);
>> + unsigned int dent_blocks = total_dent_blocks % BLKS_PER_SEC(sbi);
>>
>> if (unlikely(is_sbi_flag_set(sbi, SBI_POR_DOING)))
>> return false;
>>
>> - if (free_sections(sbi) + freed == reserved_sections(sbi) + needed &&
>> - has_curseg_enough_space(sbi))
>> - return false;
>> - return (free_sections(sbi) + freed) <=
>> - (node_secs + 2 * dent_secs + imeta_secs +
>> - reserved_sections(sbi) + needed);
>> + if (free_sections(sbi) + freed <=
>> + node_secs + dent_secs + reserved_sections(sbi) + needed)
>> + return true;
>> + if (!has_curseg_enough_space(sbi, node_blocks, dent_blocks))
>> + return true;
>> + return false;
>> }
>>
>> static inline bool f2fs_is_checkpoint_ready(struct f2fs_sb_info *sbi)
>> --
>> 2.32.0
On 04/30, Chao Yu wrote:
> As Yanming reported in bugzilla:
>
> https://bugzilla.kernel.org/show_bug.cgi?id=215914
>
> The root cause is: in a very small sized image, it's very easy to
> exceed threshold of foreground GC, if we calculate free space and
> dirty data based on section granularity, in corner case,
> has_not_enough_free_secs() will always return true, result in
> deadloop in f2fs_gc().
Performance regression was reported. Can we check this for very small sized
image only?
>
> So this patch refactors has_not_enough_free_secs() as below to fix
> this issue:
> 1. calculate needed space based on block granularity, and separate
> all blocks to two parts, section part, and block part, comparing
> section part to free section, and comparing block part to free space
> in openned log.
> 2. account F2FS_DIRTY_NODES, F2FS_DIRTY_IMETA and F2FS_DIRTY_DENTS
> as node block consumer;
> 3. account F2FS_DIRTY_DENTS as data block consumer;
>
> Cc: [email protected]
> Reported-by: Ming Yan <[email protected]>
> Signed-off-by: Chao Yu <[email protected]>
> ---
> fs/f2fs/segment.h | 30 +++++++++++++++++-------------
> 1 file changed, 17 insertions(+), 13 deletions(-)
>
> diff --git a/fs/f2fs/segment.h b/fs/f2fs/segment.h
> index 8a591455d796..28f7aa9b40bf 100644
> --- a/fs/f2fs/segment.h
> +++ b/fs/f2fs/segment.h
> @@ -575,11 +575,10 @@ static inline int reserved_sections(struct f2fs_sb_info *sbi)
> return GET_SEC_FROM_SEG(sbi, reserved_segments(sbi));
> }
>
> -static inline bool has_curseg_enough_space(struct f2fs_sb_info *sbi)
> +static inline bool has_curseg_enough_space(struct f2fs_sb_info *sbi,
> + unsigned int node_blocks, unsigned int dent_blocks)
> {
> - unsigned int node_blocks = get_pages(sbi, F2FS_DIRTY_NODES) +
> - get_pages(sbi, F2FS_DIRTY_DENTS);
> - unsigned int dent_blocks = get_pages(sbi, F2FS_DIRTY_DENTS);
> +
> unsigned int segno, left_blocks;
> int i;
>
> @@ -605,19 +604,24 @@ static inline bool has_curseg_enough_space(struct f2fs_sb_info *sbi)
> static inline bool has_not_enough_free_secs(struct f2fs_sb_info *sbi,
> int freed, int needed)
> {
> - int node_secs = get_blocktype_secs(sbi, F2FS_DIRTY_NODES);
> - int dent_secs = get_blocktype_secs(sbi, F2FS_DIRTY_DENTS);
> - int imeta_secs = get_blocktype_secs(sbi, F2FS_DIRTY_IMETA);
> + unsigned int total_node_blocks = get_pages(sbi, F2FS_DIRTY_NODES) +
> + get_pages(sbi, F2FS_DIRTY_DENTS) +
> + get_pages(sbi, F2FS_DIRTY_IMETA);
> + unsigned int total_dent_blocks = get_pages(sbi, F2FS_DIRTY_DENTS);
> + unsigned int node_secs = total_node_blocks / BLKS_PER_SEC(sbi);
> + unsigned int dent_secs = total_dent_blocks / BLKS_PER_SEC(sbi);
> + unsigned int node_blocks = total_node_blocks % BLKS_PER_SEC(sbi);
> + unsigned int dent_blocks = total_dent_blocks % BLKS_PER_SEC(sbi);
>
> if (unlikely(is_sbi_flag_set(sbi, SBI_POR_DOING)))
> return false;
>
> - if (free_sections(sbi) + freed == reserved_sections(sbi) + needed &&
> - has_curseg_enough_space(sbi))
> - return false;
> - return (free_sections(sbi) + freed) <=
> - (node_secs + 2 * dent_secs + imeta_secs +
> - reserved_sections(sbi) + needed);
> + if (free_sections(sbi) + freed <=
> + node_secs + dent_secs + reserved_sections(sbi) + needed)
> + return true;
> + if (!has_curseg_enough_space(sbi, node_blocks, dent_blocks))
> + return true;
> + return false;
> }
>
> static inline bool f2fs_is_checkpoint_ready(struct f2fs_sb_info *sbi)
> --
> 2.32.0