Re: [PATCH] f2fs: do decrease_sleep_time() if any of the victims have been selected

[Yuwei Guan]

在 2022/12/11 10:52, Chao Yu 写道:
> On 2022/12/9 19:28, Yuwei Guan wrote:
> > In non-foreground gc mode, if no victim is selected, the gc process
> > will wait for no_gc_sleep_time before waking up again. In this
> > subsequent time, even though a victim will be selected, the gc process
> > still waits for no_gc_sleep_time before waking up. The configuration
> > of wait_ms is not reasonable.
> >
> > After any of the victims have been selected, we need to do
> > decrease_sleep_time() to reduce wait_ms.
> >
> > If it is GC_URGENT_HIGH or GC_URGENT_MID gc mode,
> > wait_ms will keep urgent_sleep_time after executing 
> > decrease_sleep_time().
> >
> > In decrease_sleep_time() wait_time will be reduced to max_sleep_time
> > from no_gc_sleep_time, if *wait is no_gc_sleep_time. And then it goes
> > down in the next step.
> >
> > Signed-off-by: Yuwei Guan <Yuwei.Guan@xxxxxxxxxxxxx>
> > ---
> >   fs/f2fs/gc.c | 2 ++
> >   fs/f2fs/gc.h | 7 ++++++-
> >   2 files changed, 8 insertions(+), 1 deletion(-)
> >
> > diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
> > index f0c6506d8975..c023ffeb9268 100644
> > --- a/fs/f2fs/gc.c
> > +++ b/fs/f2fs/gc.c
> > @@ -141,6 +141,8 @@ static int gc_thread_func(void *data)
> >               /* don't bother wait_ms by foreground gc */
> >               if (!foreground)
> >                   wait_ms = gc_th->no_gc_sleep_time;
> > +        } else {
> > +            decrease_sleep_time(gc_th, &wait_ms);
>
> Once BGGC selects valid victim, it will go faster and fater?
> > How about:
>
>      } else {
>          /* reset wait_ms to default sleep time */
>          if (wait_ms == gc_th->no_gc_sleep_time)
>              wait_ms = gc_th->min_sleep_time;
>      }
Indeed. it will go faster and fater, until wait_ms reduces to 
min_sleep_time. But your suggestion seems more reasonable, I will send 
it in v2 patch.
> Thanks,
>
> >           }
> >           if (foreground)
> > diff --git a/fs/f2fs/gc.h b/fs/f2fs/gc.h
> > index 19b956c2d697..6402584dcd72 100644
> > --- a/fs/f2fs/gc.h
> > +++ b/fs/f2fs/gc.h
> > @@ -150,8 +150,13 @@ static inline void decrease_sleep_time(struct 
> > f2fs_gc_kthread *gc_th,
> >   {
> >       unsigned int min_time = gc_th->min_sleep_time;
> > -    if (*wait == gc_th->no_gc_sleep_time)
> > +    if (*wait == gc_th->urgent_sleep_time)
> > +        return;
> > +
> > +    if (*wait == gc_th->no_gc_sleep_time) {
> >           *wait = gc_th->max_sleep_time;
> > +        return;
> > +    }
> >       if ((long long)*wait - (long long)min_time < (long long)min_time)
> >           *wait = min_time;