On Wed 09-01-19 21:01:01, Kanchan Joshi wrote: > For NAND based SSDs, mixing of data with different life-time reduces > efficiency of internal garbage-collection. During FS operations, series > of journal updates will follow/precede series of data/meta updates, causing > intermixing inside SSD. By passing a write-hint with journal, its write > can be isolated from other data/meta writes, leading to endurance/performance > benefit on SSD. > > This patch introduces "j_writehint" member in JBD2 journal, using which > Ext4 specifies write-hint (as SHORT) for journal. > > Signed-off-by: Kanchan Joshi <joshi.k@xxxxxxxxxxx> Thanks for the patch. It looks mostly good, just one nit below. > diff --git a/fs/ext4/super.c b/fs/ext4/super.c > index d6c142d..3af4049 100644 > --- a/fs/ext4/super.c > +++ b/fs/ext4/super.c > @@ -4289,6 +4289,8 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent) > > set_task_ioprio(sbi->s_journal->j_task, journal_ioprio); > > + sbi->s_journal->j_writehint = KERN_WRITE_LIFE_SHORT; > + > sbi->s_journal->j_commit_callback = ext4_journal_commit_callback; So I'd rather have defines like: #define EXT4_WRITE_HINT_JOURNAL KERN_WRITE_HINT_MIN like I suggested in another email and then later we could add stuff like #define EXT4_WRITE_HINT_BITMAP (KERN_WRITE_HINT_MIN + 1) etc. Honza -- Jan Kara <jack@xxxxxxxx> SUSE Labs, CR
