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

["Darrick J. Wong" <djwong@kernel.org>]

On Fri, Jun 21, 2024 at 10:46:45AM -0700, Darrick J. Wong wrote:
> On Fri, Jun 21, 2024 at 07:48:08AM +0200, Christoph Hellwig wrote:
> > 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.
> 
> <nod> I'll await a response on this...

<shrug> No response after 11 days, I'll not hold this up further over a
minor point.

Reviewed-by: Darrick J. Wong <djwong@kernel.org>

--D


> > > 
> > > > 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).
> 
> It probably helps that dquot "clusters" are also single fsblocks too.
> 
> > 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.
> 
> Oh right, because only the AIL flushes logged buffers to disk.
> 
> --D
>