Re: [PATCH 7/9] writeback: periodically trim the writeback list

From: Jan Kara
Date: Mon Mar 16 2015 - 07:43:50 EST


On Mon 16-03-15 11:16:08, Jan Kara wrote:
> On Tue 10-03-15 15:45:22, Josef Bacik wrote:
> > From: Dave Chinner <dchinner@xxxxxxxxxx>
> >
> > Inodes are removed lazily from the bdi writeback list, so in the
> > absence of sync(2) work inodes will build up on the bdi writback
> > list even though they are no longer under IO. Use the periodic
> > kupdate work check to remove inodes no longer under IO from the
> > writeback list.
> >
> > Signed-off-by: Dave Chinner <dchinner@xxxxxxxxxx>
> Looks good. You can add:
> Reviewed-by: Jan Kara <jack@xxxxxxx>
BTW, it would be nice to add here some numbers showing how sync was
speeded up with the last two patches. The change makes a lot of sense but
it would be nice as a sanity check...

Honza

> > ---
> > fs/fs-writeback.c | 19 +++++++++++++++++++
> > 1 file changed, 19 insertions(+)
> >
> > diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
> > index 82b0f43..aa0de0f 100644
> > --- a/fs/fs-writeback.c
> > +++ b/fs/fs-writeback.c
> > @@ -1037,6 +1037,23 @@ static long wb_check_background_flush(struct bdi_writeback *wb)
> > return 0;
> > }
> >
> > +/*
> > + * clean out writeback list for all inodes that don't have IO in progress
> > + */
> > +static void wb_trim_writeback_list(struct bdi_writeback *wb)
> > +{
> > + struct inode *inode;
> > + struct inode *tmp;
> > +
> > + spin_lock(&wb->list_lock);
> > + list_for_each_entry_safe(inode, tmp, &wb->b_writeback, i_wb_list) {
> > + if (!mapping_tagged(inode->i_mapping, PAGECACHE_TAG_WRITEBACK))
> > + list_del_init(&inode->i_wb_list);
> > + }
> > + spin_unlock(&wb->list_lock);
> > +
> > +}
> > +
> > static long wb_check_old_data_flush(struct bdi_writeback *wb)
> > {
> > unsigned long expired;
> > @@ -1053,6 +1070,8 @@ static long wb_check_old_data_flush(struct bdi_writeback *wb)
> > if (time_before(jiffies, expired))
> > return 0;
> >
> > + wb_trim_writeback_list(wb);
> > +
> > wb->last_old_flush = jiffies;
> > nr_pages = get_nr_dirty_pages();
> >
> > --
> > 1.9.3
> >
> --
> Jan Kara <jack@xxxxxxx>
> SUSE Labs, CR
--
Jan Kara <jack@xxxxxxx>
SUSE Labs, CR
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