From: Dave Chinner <david@fromorbit.com>
To: Christoph Hellwig <hch@infradead.org>
Cc: xfs@oss.sgi.com
Subject: Re: [PATCH] xfs: reduce lock traffic on incore sb lock
Date: Wed, 29 Sep 2010 16:28:34 +1000 [thread overview]
Message-ID: <20100929062834.GM5665@dastard> (raw)
In-Reply-To: <20100929061351.GA20921@infradead.org>
On Wed, Sep 29, 2010 at 02:13:51AM -0400, Christoph Hellwig wrote:
> On Wed, Sep 29, 2010 at 03:57:48PM +1000, Dave Chinner wrote:
> > FWIW, I've got a prototype that converts the per-cpu counters to the
> > generic per-cpu counter infrastructure. It chops out almost all the
> > xfs_icsb_* stuff (including xfs_icsb_modify_counters()) and has a
> > diffstat of:
>
> Sounds good - I always throught of the balanced per-cpu counters as
> infrastructure that really shouldn't sit inside XFS.
The only reason I implemented them like that in the first place was
that there was no generic per-cpu counter infrastructure in
2.6.15... ;)
> > It needs a significant cleanup of xfs_mod_incore_sb() before/after
> > the conversion which I haven't done yet because I haven't quite got
> > my new percpu_counter_test_and_add_delta() function working
> > correctly yet. I spotted this locking problem when testing the
> > patch...
> >
> > That said, there's no reason why my percpu counter code needs to run
> > through xfs_mod_incore_sb() at all. If we have a separate path for
> > per-cpu counters then I can rework my code on top of that....
>
> We'll always need a low-level function to to the actual superblock
> updates and a high-level one modifying the per-cpu counters. I don't
> think the exact naming matters too much.
Agreed. I think it's probably best to wait for your cleanup patches
before reworking the counter implementation completely, though.
Cheers,
Dave.
--
Dave Chinner
david@fromorbit.com
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prev parent reply other threads:[~2010-09-29 6:27 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-09-29 0:51 [PATCH] xfs: reduce lock traffic on incore sb lock Dave Chinner
2010-09-29 4:04 ` Christoph Hellwig
2010-09-29 5:57 ` Dave Chinner
2010-09-29 6:13 ` Christoph Hellwig
2010-09-29 6:28 ` Dave Chinner [this message]
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