Re: [RFC PATHC 1/2] f2fs: apply write hints to select the type of segments for buffered write

[Jaegeuk Kim]

On 11/09, Chao Yu wrote:
> On 2017/11/9 13:51, Hyunchul Lee wrote:
> > From: Hyunchul Lee <cheol.lee@xxxxxxx>
> > 
> > Write hints helps F2FS to determine which type of segments would be
> > selected for buffered write.
> > 
> > This patch implements the mapping from write hints to segment types
> > as shown below.
> > 
> >   hints               segment type
> >   -----               ------------
> >   WRITE_LIFE_SHORT    CURSEG_COLD_DATA
> >   WRITE_LIFE_EXTREME  CURSEG_HOT_DATA
> 
> Should keep consistent with code implementation.

Merged with this fix. ;)

> 
> 	WRITE_LIFE_SHORT    CURSEG_HOT_DATA
> 	WRITE_LIFE_EXTREME  CURSEG_COLD_DATA
> 
> >   others              CURSEG_WARM_DATA
> > 
> > the F2FS poliy for hot/cold seperation has precedence over this hints.
> > And hints are not applied in in-place update.
> > 
> > Signed-off-by: Hyunchul Lee <cheol.lee@xxxxxxx>
> 
> Reviewed-by: Chao Yu <yuchao0@xxxxxxxxxx>
> 
> Thanks,
> 
> > ---
> >  fs/f2fs/segment.c | 14 +++++++++++++-
> >  1 file changed, 13 insertions(+), 1 deletion(-)
> > 
> > diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
> > index c695ff4..45aef53 100644
> > --- a/fs/f2fs/segment.c
> > +++ b/fs/f2fs/segment.c
> > @@ -2258,6 +2258,18 @@ static bool __has_curseg_space(struct f2fs_sb_info *sbi, int type)
> >  	return false;
> >  }
> >  
> > +int rw_hint_to_seg_type(enum rw_hint hint)
> > +{
> > +	switch (hint) {
> > +	case WRITE_LIFE_SHORT:
> > +		return CURSEG_HOT_DATA;
> > +	case WRITE_LIFE_EXTREME:
> > +		return CURSEG_COLD_DATA;
> > +	default:
> > +		return CURSEG_WARM_DATA;
> > +	}
> > +}
> > +
> >  static int __get_segment_type_2(struct f2fs_io_info *fio)
> >  {
> >  	if (fio->type == DATA)
> > @@ -2292,7 +2304,7 @@ static int __get_segment_type_6(struct f2fs_io_info *fio)
> >  			return CURSEG_COLD_DATA;
> >  		if (is_inode_flag_set(inode, FI_HOT_DATA))
> >  			return CURSEG_HOT_DATA;
> > -		return CURSEG_WARM_DATA;
> > +		return rw_hint_to_seg_type(inode->i_write_hint);
> >  	} else {
> >  		if (IS_DNODE(fio->page))
> >  			return is_cold_node(fio->page) ? CURSEG_WARM_NODE :
> >