Re: [PATCH 11/11] xfs: skip flushing log items during push

[Christoph Hellwig <hch@lst.de>]

On Thu, Jun 20, 2024 at 12:51:42PM -0700, Darrick J. Wong wrote:
> > Further with no backoff we don't need to gather huge delwri lists to
> > mitigate the impact of backoffs, so we can submit IO more frequently
> > and reduce the time log items spend in flushing state by breaking
> > out of the item push loop once we've gathered enough IO to batch
> > submission effectively.
> 
> Is that what the new count > 1000 branch does?

That's my interpreation anyway.  I'll let Dave chime in if he disagrees.

> 
> > Signed-off-by: Dave Chinner <dchinner@redhat.com>
> > ---
> >  fs/xfs/xfs_inode.c      | 1 +
> >  fs/xfs/xfs_inode_item.c | 6 +++++-
> 
> Does it make sense to do this for buffer or dquot items too?

Not having written this here is my 2 unqualified cents:

For dquots it looks like it could be easily ported over, but I guess no
one has been bothering with dquot performance work for a while as it's
also missing a bunch of other things we did to the inode.  But given that
according to Dave's commit log the іnode cluster flushing is a big part
of this dquots probably aren't as affected anyway as we flush them
individually (and there generally are a lot fewer dquot items in the AIL
anyway).

For buf items the buffers are queued up on the on-stack delwri list
and written when we flush them.  So we won't ever find already
flushing items.