Re: [PATCH 1/4] xfs: do not update xa_last_pushed_lsn for locked items

Alex Elder
2011-10-07T22:18:10Z

On Thu, 2011-10-06 at 14:32 -0400, Christoph Hellwig wrote:
> If an item was locked we should not update xa_last_pushed_lsn and thus skip
> it when restarting the AIL scan as we need to be able to lock and write it
> out as soon as possible. Otherwise heavy lock contention might starve AIL
> pushing too easily, especially given the larger backoff once we moved
> xa_last_pushed_lsn all the way to the target lsn.
>
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> Reported-by: Stefan Priebe <s.priebe@profihost.ag>
> Tested-by: Stefan Priebe <s.priebe@profihost.ag>

I remember wondering about that one line during review, but
I believe I reasoned something about the "already being
reflushed or relogged" made it the right thing to do.

Your explanation makes sense though (but what do I know,
the original code seemed OK too...).

Reviewed-by: Alex Elder <aelder@sgi.com>