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Date: Wed, 5 Jun 2024 14:26:42 +0800
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Subject: Re: [PATCH] f2fs: enable atgc if atgc_age_threshold from user is less
 than elapsed_time
To: Zhiguo Niu <niuzhiguo84@gmail.com>
Cc: Zhiguo Niu <zhiguo.niu@unisoc.com>, jaegeuk@kernel.org,
 linux-f2fs-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org,
 ke.wang@unisoc.com
References: <1716204978-29455-1-git-send-email-zhiguo.niu@unisoc.com>
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From: Chao Yu <chao@kernel.org>
In-Reply-To: <CAHJ8P3K_u=ZmXaMF5jUu_MPSJPAhKmEx4hyaTinMQ=nnLQ9aRA@mail.gmail.com>
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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;