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From: Zhiguo Niu <niuzhiguo84@gmail.com>
Date: Wed, 5 Jun 2024 14:16:40 +0800
Message-ID: <CAHJ8P3LgbpLZhP3+maGXpuwsSzn20Kw5Rgdwsb7y1q5BfTyrwQ@mail.gmail.com>
Subject: Re: [PATCH] f2fs: enable atgc if atgc_age_threshold from user is less
 than elapsed_time
To: Chao Yu <chao@kernel.org>
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
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On Wed, Jun 5, 2024 at 1:59=E2=80=AFPM Zhiguo Niu <niuzhiguo84@gmail.com> w=
rote:
>
> On Wed, Jun 5, 2024 at 11:48=E2=80=AFAM Chao Yu <chao@kernel.org> wrote:
> >
> > On 2024/6/3 17:05, Zhiguo Niu wrote:
> > > On Mon, Jun 3, 2024 at 3:41=E2=80=AFPM Chao Yu <chao@kernel.org> wrot=
e:
> > >>
> > >> 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 ca=
n
> > >>> not work even the above conditions met.
> > >>>
> > >>> It is better to enable atgc dynamiclly when user change atgc_age_th=
reshold
> > >>> 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, i=
nt 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 =3D CURSEG_I(sbi, CURSEG_ALL_DATA=
_ATGC);
> > >>>        int ret =3D 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 f2f=
s_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, i=
nt 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 =3D t;
> > >>> +             if (sbi->am.atgc_enabled)
> > >>> +                     return count;
> > >>> +
> > >>> +             if (test_opt(sbi, ATGC) &&
> > >>> +                     le64_to_cpu(sbi->ckpt->elapsed_time) >=3D 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 >=3D DEF_GC_THREAD_AGE_THR=
ESHOLD)
> > >>                  am->atgc_enabled =3D true;
> > >>
> > >> What about enabling atgc_enabled during checkpoint once elapsed time=
 is
> > >> satisfed w/ the condition? I guess this can give another chance when=
ever
> > >> 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 co=
nsumed
> > by initialization of atgc curseg.
> >
> > > 2. dynamically enabling atgc may have other problems. Is this confirm=
ed?
> >
> > 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 *sb=
i, 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_in=
fo *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 ty=
pe,
> > 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_inf=
o *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 forc=
e)
> >   {
> >         struct curseg_info *curseg =3D CURSEG_I(sbi, CURSEG_ALL_DATA_AT=
GC);
> >         int ret =3D 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=3Dfalse.
> Or am I missing something?
hi Chao,
sorry, I read && as || ,  Please ignore the above comment,
but Is it still OK without the  "force"  parameter?
thanks=EF=BC=81
> >                 return 0;
> >
> >         f2fs_down_read(&SM_I(sbi)->curseg_lock);
> > @@ -2971,9 +2971,29 @@ static int __f2fs_init_atgc_curseg(struct f2fs_s=
b_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?
> thanks!
> > +               return 0;
> > +
> > +       ret =3D __f2fs_init_atgc_curseg(sbi, true);
> > +       if (!ret) {
> > +               sbi->am.atgc_enabled =3D true;
> > +               f2fs_info(sbi, "reenabled age threshold GC");
> > +       }
> > +       return ret;
> >   }
> >
> >   static void __f2fs_save_inmem_curseg(struct f2fs_sb_info *sbi, int ty=
pe)
> > --
> > 2.40.1
> >
> > > thanks=EF=BC=81
> > >>
> > >> Thanks,
> > >>
> > >>> +                     if (f2fs_init_atgc_curseg(sbi))
> > >>> +                             return -EINVAL;
> > >>> +                     sbi->am.atgc_enabled =3D true;
> > >>> +             }
> > >>> +             return count;
> > >>> +     }
> > >>> +
> > >>>        if (!strcmp(a->attr.name, "gc_segment_mode")) {
> > >>>                if (t < MAX_GC_MODE)
> > >>>                        sbi->gc_segment_mode =3D t;