2020-06-30 10:05:24

by Chao Yu

Subject: [PATCH RFC 2/5] f2fs: record average update time of segment

Previously, once we update one block in segment, we will update mtime of
segment to last time, making aged segment becoming freshest, result in
that GC with cost benefit algorithm missing such segment, So this patch
changes to record mtime as average block updating time instead of last
updating time.

It's not needed to reset mtime for prefree segment, as se->valid_blocks
is zero, then old se->mtime won't take any weight with below calculation:

se->mtime = (se->mtime * se->valid_blocks + mtime) /
(se->valid_blocks + 1);

Signed-off-by: Chao Yu <[email protected]>
---
fs/f2fs/segment.c | 21 ++++++++++++++++++---
1 file changed, 18 insertions(+), 3 deletions(-)

diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index 863ec6f1fb87..906c313835ad 100644
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -2150,6 +2150,22 @@ static void __set_sit_entry_type(struct f2fs_sb_info *sbi, int type,
__mark_sit_entry_dirty(sbi, segno);
}

+static void update_segment_mtime(struct f2fs_sb_info *sbi, block_t blkaddr)
+{
+ unsigned int segno = GET_SEGNO(sbi, blkaddr);
+ struct seg_entry *se = get_seg_entry(sbi, segno);
+ unsigned long long mtime = get_mtime(sbi, false);
+
+ if (!se->mtime) {
+ se->mtime = mtime;
+ } else {
+ se->mtime = (se->mtime * se->valid_blocks + mtime) /
+ (se->valid_blocks + 1);
+ }
+ if (mtime > SIT_I(sbi)->max_mtime)
+ SIT_I(sbi)->max_mtime = mtime;
+}
+
static void update_sit_entry(struct f2fs_sb_info *sbi, block_t blkaddr, int del)
{
struct seg_entry *se;
@@ -2169,10 +2185,9 @@ static void update_sit_entry(struct f2fs_sb_info *sbi, block_t blkaddr, int del)
f2fs_bug_on(sbi, (new_vblocks >> (sizeof(unsigned short) << 3) ||
(new_vblocks > sbi->blocks_per_seg)));

+ update_segment_mtime(sbi, blkaddr);
+
se->valid_blocks = new_vblocks;
- se->mtime = get_mtime(sbi, false);
- if (se->mtime > SIT_I(sbi)->max_mtime)
- SIT_I(sbi)->max_mtime = se->mtime;

/* Update valid block bitmap */
if (del > 0) {
--
2.26.2

2020-07-01 16:20:21

by Jaegeuk Kim

Subject: Re: [PATCH RFC 2/5] f2fs: record average update time of segment

On 06/30, Chao Yu wrote:
> Previously, once we update one block in segment, we will update mtime of
> segment to last time, making aged segment becoming freshest, result in
> that GC with cost benefit algorithm missing such segment, So this patch
> changes to record mtime as average block updating time instead of last
> updating time.
>
> It's not needed to reset mtime for prefree segment, as se->valid_blocks
> is zero, then old se->mtime won't take any weight with below calculation:
>
> se->mtime = (se->mtime * se->valid_blocks + mtime) /
> (se->valid_blocks + 1);
>
> Signed-off-by: Chao Yu <[email protected]>
> ---
> fs/f2fs/segment.c | 21 ++++++++++++++++++---
> 1 file changed, 18 insertions(+), 3 deletions(-)
>
> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
> index 863ec6f1fb87..906c313835ad 100644
> --- a/fs/f2fs/segment.c
> +++ b/fs/f2fs/segment.c
> @@ -2150,6 +2150,22 @@ static void __set_sit_entry_type(struct f2fs_sb_info *sbi, int type,
> __mark_sit_entry_dirty(sbi, segno);
> }
>
> +static void update_segment_mtime(struct f2fs_sb_info *sbi, block_t blkaddr)
> +{
> + unsigned int segno = GET_SEGNO(sbi, blkaddr);
> + struct seg_entry *se = get_seg_entry(sbi, segno);
> + unsigned long long mtime = get_mtime(sbi, false);
> +
> + if (!se->mtime) {

Don't need {}.

> + se->mtime = mtime;
> + } else {
> + se->mtime = (se->mtime * se->valid_blocks + mtime) /
> + (se->valid_blocks + 1);
> + }
> + if (mtime > SIT_I(sbi)->max_mtime)
> + SIT_I(sbi)->max_mtime = mtime;
> +}
> +
> static void update_sit_entry(struct f2fs_sb_info *sbi, block_t blkaddr, int del)
> {
> struct seg_entry *se;
> @@ -2169,10 +2185,9 @@ static void update_sit_entry(struct f2fs_sb_info *sbi, block_t blkaddr, int del)
> f2fs_bug_on(sbi, (new_vblocks >> (sizeof(unsigned short) << 3) ||
> (new_vblocks > sbi->blocks_per_seg)));
>
> + update_segment_mtime(sbi, blkaddr);
> +
> se->valid_blocks = new_vblocks;
> - se->mtime = get_mtime(sbi, false);
> - if (se->mtime > SIT_I(sbi)->max_mtime)
> - SIT_I(sbi)->max_mtime = se->mtime;
>
> /* Update valid block bitmap */
> if (del > 0) {
> --
> 2.26.2

2020-07-03 02:14:54

by Chao Yu

Subject: Re: [PATCH RFC 2/5] f2fs: record average update time of segment

On 2020/7/2 0:19, Jaegeuk Kim wrote:
> On 06/30, Chao Yu wrote:
>> Previously, once we update one block in segment, we will update mtime of
>> segment to last time, making aged segment becoming freshest, result in
>> that GC with cost benefit algorithm missing such segment, So this patch
>> changes to record mtime as average block updating time instead of last
>> updating time.
>>
>> It's not needed to reset mtime for prefree segment, as se->valid_blocks
>> is zero, then old se->mtime won't take any weight with below calculation:
>>
>> se->mtime = (se->mtime * se->valid_blocks + mtime) /
>> (se->valid_blocks + 1);
>>
>> Signed-off-by: Chao Yu <[email protected]>
>> ---
>> fs/f2fs/segment.c | 21 ++++++++++++++++++---
>> 1 file changed, 18 insertions(+), 3 deletions(-)
>>
>> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
>> index 863ec6f1fb87..906c313835ad 100644
>> --- a/fs/f2fs/segment.c
>> +++ b/fs/f2fs/segment.c
>> @@ -2150,6 +2150,22 @@ static void __set_sit_entry_type(struct f2fs_sb_info *sbi, int type,
>> __mark_sit_entry_dirty(sbi, segno);
>> }
>>
>> +static void update_segment_mtime(struct f2fs_sb_info *sbi, block_t blkaddr)
>> +{
>> + unsigned int segno = GET_SEGNO(sbi, blkaddr);
>> + struct seg_entry *se = get_seg_entry(sbi, segno);
>> + unsigned long long mtime = get_mtime(sbi, false);
>> +
>> + if (!se->mtime) {
>
> Don't need {}.

Updated,

BTW, have fixed below compile error:

m68k-linux-ld: fs/f2fs/segment.o: in function `update_segment_mtime':
fs/f2fs/segment.c:2162: undefined reference to `__udivdi3'

Thanks,

>
>> + se->mtime = mtime;
>> + } else {
>> + se->mtime = (se->mtime * se->valid_blocks + mtime) /
>> + (se->valid_blocks + 1);
>> + }
>> + if (mtime > SIT_I(sbi)->max_mtime)
>> + SIT_I(sbi)->max_mtime = mtime;
>> +}
>> +
>> static void update_sit_entry(struct f2fs_sb_info *sbi, block_t blkaddr, int del)
>> {
>> struct seg_entry *se;
>> @@ -2169,10 +2185,9 @@ static void update_sit_entry(struct f2fs_sb_info *sbi, block_t blkaddr, int del)
>> f2fs_bug_on(sbi, (new_vblocks >> (sizeof(unsigned short) << 3) ||
>> (new_vblocks > sbi->blocks_per_seg)));
>>
>> + update_segment_mtime(sbi, blkaddr);
>> +
>> se->valid_blocks = new_vblocks;
>> - se->mtime = get_mtime(sbi, false);
>> - if (se->mtime > SIT_I(sbi)->max_mtime)
>> - SIT_I(sbi)->max_mtime = se->mtime;
>>
>> /* Update valid block bitmap */
>> if (del > 0) {
>> --
>> 2.26.2
> .
>