by Zhiguo Niu

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

On Wed, Jun 5, 2024 at 2:26 PM Chao Yu <[email protected]> wrote:
>
> On 2024/6/5 13:59, Zhiguo Niu wrote:
> > On Wed, Jun 5, 2024 at 11:48 AM Chao Yu <[email protected]> wrote:
> >>
> >> On 2024/6/3 17:05, Zhiguo Niu wrote:
> >>> On Mon, Jun 3, 2024 at 3:41 PM Chao Yu <[email protected]> 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 <[email protected]>
> >>>>> ---
> >>>>> 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?
Hi Chao,
OK, and I will also verify the basic function.
thanks！
>
> 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;