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Message-ID: <028d6892-f26f-479a-b27e-544d366d27f1@oppo.com>
Date: Thu, 12 Sep 2024 13:16:07 +0800
From: liuderong <liuderong@...o.com>
To: Chao Yu <chao@...nel.org>, jaegeuk@...nel.org
Cc: linux-f2fs-devel@...ts.sourceforge.net, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1 2/2] f2fs: introduce get_section_mtime
On 2024/9/11 18:22, Chao Yu wrote:
> On 2024/9/11 10:40, liuderong@...o.com wrote:
>> From: liuderong <liuderong@...o.com>
>>
>> When segs_per_sec is larger than 1, section may contain free segments,
>> mtime should be the mean value of each valid segments,
>> so introduce get_section_mtime to exclude free segments in a section.
>>
>> Signed-off-by: liuderong <liuderong@...o.com>
>> ---
>> fs/f2fs/f2fs.h | 2 ++
>> fs/f2fs/gc.c | 15 ++-------------
>> fs/f2fs/segment.c | 49
>> ++++++++++++++++++++++++++++++++++++++++++++-----
>> 3 files changed, 48 insertions(+), 18 deletions(-)
>>
>> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
>> index 4dcdcdd..d6adf0f 100644
>> --- a/fs/f2fs/f2fs.h
>> +++ b/fs/f2fs/f2fs.h
>> @@ -3762,6 +3762,8 @@ enum rw_hint f2fs_io_type_to_rw_hint(struct
>> f2fs_sb_info *sbi,
>> unsigned int f2fs_usable_segs_in_sec(struct f2fs_sb_info *sbi);
>> unsigned int f2fs_usable_blks_in_seg(struct f2fs_sb_info *sbi,
>> unsigned int segno);
>> +unsigned long long get_section_mtime(struct f2fs_sb_info *sbi,
>> + unsigned int segno);
>>
>> #define DEF_FRAGMENT_SIZE 4
>> #define MIN_FRAGMENT_SIZE 1
>> diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
>> index 6299639..03c6117 100644
>> --- a/fs/f2fs/gc.c
>> +++ b/fs/f2fs/gc.c
>> @@ -332,20 +332,14 @@ static unsigned int check_bg_victims(struct
>> f2fs_sb_info *sbi)
>> static unsigned int get_cb_cost(struct f2fs_sb_info *sbi, unsigned
>> int segno)
>> {
>> struct sit_info *sit_i = SIT_I(sbi);
>> - unsigned int secno = GET_SEC_FROM_SEG(sbi, segno);
>> - unsigned int start = GET_SEG_FROM_SEC(sbi, secno);
>> unsigned long long mtime = 0;
>> unsigned int vblocks;
>> unsigned char age = 0;
>> unsigned char u;
>> - unsigned int i;
>> unsigned int usable_segs_per_sec =
>> f2fs_usable_segs_in_sec(sbi);
>>
>> - for (i = 0; i < usable_segs_per_sec; i++)
>> - mtime += get_seg_entry(sbi, start + i)->mtime;
>> + mtime = get_section_mtime(sbi, segno);
>> vblocks = get_valid_blocks(sbi, segno, true);
>> -
>> - mtime = div_u64(mtime, usable_segs_per_sec);
>> vblocks = div_u64(vblocks, usable_segs_per_sec);
>>
>> u = BLKS_TO_SEGS(sbi, vblocks * 100);
>> @@ -485,10 +479,7 @@ static void add_victim_entry(struct f2fs_sb_info
>> *sbi,
>> struct victim_sel_policy *p,
>> unsigned int segno)
>> {
>> struct sit_info *sit_i = SIT_I(sbi);
>> - unsigned int secno = GET_SEC_FROM_SEG(sbi, segno);
>> - unsigned int start = GET_SEG_FROM_SEC(sbi, secno);
>> unsigned long long mtime = 0;
>> - unsigned int i;
>>
>> if (unlikely(is_sbi_flag_set(sbi, SBI_CP_DISABLED))) {
>> if (p->gc_mode == GC_AT &&
>> @@ -496,9 +487,7 @@ static void add_victim_entry(struct f2fs_sb_info
>> *sbi,
>> return;
>> }
>>
>> - for (i = 0; i < SEGS_PER_SEC(sbi); i++)
>> - mtime += get_seg_entry(sbi, start + i)->mtime;
>> - mtime = div_u64(mtime, SEGS_PER_SEC(sbi));
>> + mtime = get_section_mtime(sbi, segno);
>>
>> /* Handle if the system time has changed by the user */
>> if (mtime < sit_i->min_mtime)
>> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
>> index 6627394..b63f35fa 100644
>> --- a/fs/f2fs/segment.c
>> +++ b/fs/f2fs/segment.c
>> @@ -5389,6 +5389,49 @@ unsigned int f2fs_usable_segs_in_sec(struct
>> f2fs_sb_info *sbi)
>> return SEGS_PER_SEC(sbi);
>> }
>>
>> +unsigned long long get_section_mtime(struct f2fs_sb_info *sbi,
>> + unsigned int segno)
>> +{
>> + unsigned int usable_segs_per_sec = f2fs_usable_segs_in_sec(sbi);
>> + unsigned int secno = 0, start = 0;
>> + struct free_segmap_info *free_i = FREE_I(sbi);
>> + unsigned int valid_seg_count = 0;
>> + unsigned long long mtime = 0;
>> + unsigned int i;
>> +
>> + if (segno == NULL_SEGNO)
>> + return 0;
>> +
>> + secno = GET_SEC_FROM_SEG(sbi, segno);
>> + start = GET_SEG_FROM_SEC(sbi, secno);
>> +
>> + for (i = 0; i < usable_segs_per_sec; i++) {
>> + /* for large section, only check the mtime of valid
>> segments */
>> + if (__is_large_section(sbi)) {
>> + spin_lock(&free_i->segmap_lock);
>> + if (test_bit(start + i, free_i->free_segmap)) {
>> + mtime += get_seg_entry(sbi, start +
>> i)->mtime;
>> + valid_seg_count++;
>> + }
>> + spin_unlock(&free_i->segmap_lock);
>> + } else {
>> + mtime += get_seg_entry(sbi, start + i)->mtime;
>> + }
>> + }
>> +
>> + if (__is_large_section(sbi)) {
>> + if (!valid_seg_count)
>> + goto out;
>> + mtime = div_u64(mtime, valid_seg_count);
>> + } else {
>> + mtime = div_u64(mtime, usable_segs_per_sec);
>> + }
>
> What about:
>
> if (!__is_large_section(sbi))
> return get_seg_entry(sbi, start + i)->mtime;
>
> for (i = 0; i < usable_segs_per_sec; i++) {
> /* for large section, only check the mtime of valid segments */
> ...
> }
>
> return div_u64(mtime, usable_segs_per_sec);
>
> Thanks,
>
OK, I will modify the code.
Thanks,
Derong
>> +
>> +out:
>> + return mtime;
>> +}
>> +
>> /*
>> * Update min, max modified time for cost-benefit GC algorithm
>> */
>> @@ -5402,13 +5445,9 @@ static void init_min_max_mtime(struct
>> f2fs_sb_info *sbi)
>> sit_i->min_mtime = ULLONG_MAX;
>>
>> for (segno = 0; segno < MAIN_SEGS(sbi); segno +=
>> SEGS_PER_SEC(sbi)) {
>> - unsigned int i;
>> unsigned long long mtime = 0;
>>
>> - for (i = 0; i < SEGS_PER_SEC(sbi); i++)
>> - mtime += get_seg_entry(sbi, segno + i)->mtime;
>> -
>> - mtime = div_u64(mtime, SEGS_PER_SEC(sbi));
>> + mtime = get_section_mtime(sbi, segno);
>>
>> if (sit_i->min_mtime > mtime)
>> sit_i->min_mtime = mtime;
>> --
>> 2.7.4
>
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