From: Dave Chinner <david@fromorbit.com>
To: Christoph Hellwig <hch@lst.de>
Cc: Brian Foster <bfoster@redhat.com>, xfs@oss.sgi.com
Subject: Re: [PATCH 3/4] xfs: make xfs_inode_set_eofblocks_tag cheaper for the common case
Date: Wed, 31 Aug 2016 09:03:20 +1000 [thread overview]
Message-ID: <20160830230320.GW19025@dastard> (raw)
In-Reply-To: <20160830144006.GA14504@lst.de>
On Tue, Aug 30, 2016 at 04:40:06PM +0200, Christoph Hellwig wrote:
> On Fri, Aug 26, 2016 at 12:02:09PM -0400, Brian Foster wrote:
> > > I don't think taking it should be too bad, but given the ops ordering
> > > it also seems entirely pointless to even take it.
> > >
> >
> > Then why are we taking it? I assumed it at least served as a memory
> > barrier...
>
> I meant to take it for that early check, not in general.
>
> I guess this is another hint we should try to look into using proper
> atomic bitops here..
I think we've looked at that in the past, but there were cases where
we have to do things atomically with setting/clearing the flags and
that required the spinlock to protect the flag modifications as
well. IIRC there are also cases where we have to check/set multiple
flags at once, which we cannot do with atomic bit ops.
Perhaps the code has changed enough that there isn't a problem
anymore, but I don't think that is the case...
Cheers,
Dave.
--
Dave Chinner
david@fromorbit.com
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next prev parent reply other threads:[~2016-08-30 23:03 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-08-21 21:51 iomap write fixes Christoph Hellwig
2016-08-21 21:51 ` [PATCH 1/4] xfs: move xfs_bmbt_to_iomap up Christoph Hellwig
2016-08-25 12:38 ` Brian Foster
2016-08-21 21:51 ` [PATCH 2/4] xfs: factor our a helper to calculate the EOF alignment Christoph Hellwig
2016-08-25 12:38 ` Brian Foster
2016-08-21 21:51 ` [PATCH 3/4] xfs: make xfs_inode_set_eofblocks_tag cheaper for the common case Christoph Hellwig
2016-08-25 12:38 ` Brian Foster
2016-08-26 14:26 ` Christoph Hellwig
2016-08-26 16:02 ` Brian Foster
2016-08-30 14:40 ` Christoph Hellwig
2016-08-30 23:03 ` Dave Chinner [this message]
2016-08-21 21:51 ` [PATCH 4/4] xfs: rewrite and optimize the delalloc write path Christoph Hellwig
2016-08-25 14:37 ` Brian Foster
2016-08-26 14:33 ` Christoph Hellwig
2016-08-26 16:03 ` Brian Foster
2016-08-26 16:07 ` Brian Foster
2016-08-30 14:44 ` Christoph Hellwig
2016-08-30 20:28 ` Brian Foster
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