Re: [PATCH] f2fs: enable atgc if atgc_age_threshold from user is less than elapsed_time

Chao Yu
2024-06-05T06:26:47Z

On 2024/6/5 13:59, Zhiguo Niu wrote:
> On Wed, Jun 5, 2024 at 11:48 AM Chao Yu <chao@kernel.org> wrote:
>>
>> On 2024/6/3 17:05, Zhiguo Niu wrote:
>>> On Mon, Jun 3, 2024 at 3:41 PM Chao Yu <chao@kernel.org> wrote:
>>>>
>>>> On 2024/5/20 19:36, Zhiguo Niu wrote:
>>>>> Now atgc can be enabled based on the following conditions:
>>>>> -ATGC mount option is set
>>>>> -elapsed_time is more than atgc_age_threshold already
>>>>> but these conditions are check when umounted->mounted device again.
>>>>> If the device has not be umounted->mounted for a long time, atgc can
>>>>> not work even the above conditions met.
>>>>>
>>>>> It is better to enable atgc dynamiclly when user change atgc_age_threshold
>>>>> meanwhile this vale is less than elapsed_time and ATGC mount option is on.
>>>>>
>>>>> Signed-off-by: Zhiguo Niu <zhiguo.niu@unisoc.com>
>>>>> ---
>>>>> fs/f2fs/f2fs.h | 1 +
>>>>> fs/f2fs/segment.c | 9 ++++-----
>>>>> fs/f2fs/sysfs.c | 16 ++++++++++++++++
>>>>> 3 files changed, 21 insertions(+), 5 deletions(-)
>>>>>
>>>>> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
>>>>> index 1974b6a..e441d2d 100644
>>>>> --- a/fs/f2fs/f2fs.h
>>>>> +++ b/fs/f2fs/f2fs.h
>>>>> @@ -3694,6 +3694,7 @@ void f2fs_clear_prefree_segments(struct f2fs_sb_info *sbi,
>>>>> int f2fs_init_inmem_curseg(struct f2fs_sb_info *sbi);
>>>>> void f2fs_save_inmem_curseg(struct f2fs_sb_info *sbi);
>>>>> void f2fs_restore_inmem_curseg(struct f2fs_sb_info *sbi);
>>>>> +int f2fs_init_atgc_curseg(struct f2fs_sb_info *sbi);
>>>>> int f2fs_allocate_segment_for_resize(struct f2fs_sb_info *sbi, int type,
>>>>> unsigned int start, unsigned int end);
>>>>> int f2fs_allocate_new_section(struct f2fs_sb_info *sbi, int type, bool force);
>>>>> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
>>>>> index 71dc8042..44923d4 100644
>>>>> --- a/fs/f2fs/segment.c
>>>>> +++ b/fs/f2fs/segment.c
>>>>> @@ -2931,14 +2931,11 @@ static int get_atssr_segment(struct f2fs_sb_info *sbi, int type,
>>>>> return ret;
>>>>> }
>>>>>
>>>>> -static int __f2fs_init_atgc_curseg(struct f2fs_sb_info *sbi)
>>>>> +int f2fs_init_atgc_curseg(struct f2fs_sb_info *sbi)
>>>>> {
>>>>> struct curseg_info *curseg = CURSEG_I(sbi, CURSEG_ALL_DATA_ATGC);
>>>>> int ret = 0;
>>>>>
>>>>> - if (!sbi->am.atgc_enabled)
>>>>> - return 0;
>>>>> -
>>>>> f2fs_down_read(&SM_I(sbi)->curseg_lock);
>>>>>
>>>>> mutex_lock(&curseg->curseg_mutex);
>>>>> @@ -2955,7 +2952,9 @@ static int __f2fs_init_atgc_curseg(struct f2fs_sb_info *sbi)
>>>>> }
>>>>> int f2fs_init_inmem_curseg(struct f2fs_sb_info *sbi)
>>>>> {
>>>>> - return __f2fs_init_atgc_curseg(sbi);
>>>>> + if (!sbi->am.atgc_enabled)
>>>>> + return 0;
>>>>> + return f2fs_init_atgc_curseg(sbi);
>>>>> }
>>>>>
>>>>> static void __f2fs_save_inmem_curseg(struct f2fs_sb_info *sbi, int type)
>>>>> diff --git a/fs/f2fs/sysfs.c b/fs/f2fs/sysfs.c
>>>>> index 09d3ecf..72676c5 100644
>>>>> --- a/fs/f2fs/sysfs.c
>>>>> +++ b/fs/f2fs/sysfs.c
>>>>> @@ -673,6 +673,22 @@ static ssize_t __sbi_store(struct f2fs_attr *a,
>>>>> return count;
>>>>> }
>>>>>
>>>>> + if (!strcmp(a->attr.name, "atgc_age_threshold")) {
>>>>> + if (t < 0)
>>>>> + return -EINVAL;
>>>>> + sbi->am.age_threshold = t;
>>>>> + if (sbi->am.atgc_enabled)
>>>>> + return count;
>>>>> +
>>>>> + if (test_opt(sbi, ATGC) &&
>>>>> + le64_to_cpu(sbi->ckpt->elapsed_time) >= t) {
>>>>
>>> Hi Chao,
>>>> Oh, I guess you want to fix this:
>>> Yes, Sorry for not making it clear before.
>>>>
>>>> static void init_atgc_management(struct f2fs_sb_info *sbi)
>>>> {
>>>> ...
>>>> if (test_opt(sbi, ATGC) &&
>>>> SIT_I(sbi)->elapsed_time >= DEF_GC_THREAD_AGE_THRESHOLD)
>>>> am->atgc_enabled = true;
>>>>
>>>> What about enabling atgc_enabled during checkpoint once elapsed time is
>>>> satisfed w/ the condition? I guess this can give another chance whenever
>>>> CP is been triggered, and it can avoid the racing condition as well.
>>> 1. I'm not sure if this will increase checkpoint time consumption?
>>
>> Since it won't increase any IO time, I guess it's fine tolerate time consumed
>> by initialization of atgc curseg.
>>
>>> 2. dynamically enabling atgc may have other problems. Is this confirmed?
>>
>> I think so, checkpoint has avoided most race cases.
>>
>> So, how do you think of below diff:
> Hi Chao,
> I think flow is ok, some details need to be discussed.
>>
>> ---
>> fs/f2fs/checkpoint.c | 2 ++
>> fs/f2fs/f2fs.h | 1 +
>> fs/f2fs/segment.c | 26 +++++++++++++++++++++++---
>> 3 files changed, 26 insertions(+), 3 deletions(-)
>>
>> diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c
>> index 55d444bec5c0..4a73bd481a25 100644
>> --- a/fs/f2fs/checkpoint.c
>> +++ b/fs/f2fs/checkpoint.c
>> @@ -1718,6 +1718,8 @@ int f2fs_write_checkpoint(struct f2fs_sb_info *sbi, struct cp_control *cpc)
>> }
>>
>> f2fs_restore_inmem_curseg(sbi);
>> + f2fs_reinit_atgc_curseg(sbi);
>> +
>> stat_inc_cp_count(sbi);
>> stop:
>> unblock_operations(sbi);
>> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
>> index 9688df332147..8d385a1c75ad 100644
>> --- a/fs/f2fs/f2fs.h
>> +++ b/fs/f2fs/f2fs.h
>> @@ -3693,6 +3693,7 @@ void f2fs_release_discard_addrs(struct f2fs_sb_info *sbi);
>> int f2fs_npages_for_summary_flush(struct f2fs_sb_info *sbi, bool for_ra);
>> bool f2fs_segment_has_free_slot(struct f2fs_sb_info *sbi, int segno);
>> int f2fs_init_inmem_curseg(struct f2fs_sb_info *sbi);
>> +int f2fs_reinit_atgc_curseg(struct f2fs_sb_info *sbi);
>> void f2fs_save_inmem_curseg(struct f2fs_sb_info *sbi);
>> void f2fs_restore_inmem_curseg(struct f2fs_sb_info *sbi);
>> int f2fs_allocate_segment_for_resize(struct f2fs_sb_info *sbi, int type,
>> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
>> index bdc2247387e8..6d4273faf061 100644
>> --- a/fs/f2fs/segment.c
>> +++ b/fs/f2fs/segment.c
>> @@ -2949,12 +2949,12 @@ static int get_atssr_segment(struct f2fs_sb_info *sbi, int type,
>> return ret;
>> }
>>
>> -static int __f2fs_init_atgc_curseg(struct f2fs_sb_info *sbi)
>> +static int __f2fs_init_atgc_curseg(struct f2fs_sb_info *sbi, bool force)
>> {
>> struct curseg_info *curseg = CURSEG_I(sbi, CURSEG_ALL_DATA_ATGC);
>> int ret = 0;
>>
>> - if (!sbi->am.atgc_enabled)
>> + if (!sbi->am.atgc_enabled && !force)
> Is this parameter "force" unnecessary?
> in mount flow, even atgc enable conditions are all met, it is not
> enabled because of force=false.
> Or am I missing something?
>> return 0;
>>
>> f2fs_down_read(&SM_I(sbi)->curseg_lock);
>> @@ -2971,9 +2971,29 @@ static int __f2fs_init_atgc_curseg(struct f2fs_sb_info *sbi)
>> f2fs_up_read(&SM_I(sbi)->curseg_lock);
>> return ret;
>> }
>> +
>> int f2fs_init_inmem_curseg(struct f2fs_sb_info *sbi)
>> {
>> - return __f2fs_init_atgc_curseg(sbi);
>> + return __f2fs_init_atgc_curseg(sbi, false);
>> +}
>> +
>> +int f2fs_reinit_atgc_curseg(struct f2fs_sb_info *sbi)
>> +{
>> + int ret;
>> +
>> + if (!test_opt(sbi, ATGC))
>> + return 0;
>> + if (sbi->am.atgc_enabled)
>> + return 0;
>> + if (SIT_I(sbi)->elapsed_time < sbi->am.age_threshold)
> SIT(sbi)->elapsed_time is just updated in mount flow, so
> ckpt->elapsed_time is more suitable here?

Agreed, it needs to be fixed.

Can you please update those changes into v2?

Thanks,

> thanks!
>> + return 0;
>> +
>> + ret = __f2fs_init_atgc_curseg(sbi, true);
>> + if (!ret) {
>> + sbi->am.atgc_enabled = true;
>> + f2fs_info(sbi, "reenabled age threshold GC");
>> + }
>> + return ret;
>> }
>>
>> static void __f2fs_save_inmem_curseg(struct f2fs_sb_info *sbi, int type)
>> --
>> 2.40.1
>>
>>> thanks！
>>>>
>>>> Thanks,
>>>>
>>>>> + if (f2fs_init_atgc_curseg(sbi))
>>>>> + return -EINVAL;
>>>>> + sbi->am.atgc_enabled = true;
>>>>> + }
>>>>> + return count;
>>>>> + }
>>>>> +
>>>>> if (!strcmp(a->attr.name, "gc_segment_mode")) {
>>>>> if (t < MAX_GC_MODE)
>>>>> sbi->gc_segment_mode = t;