From: Christoph Hellwig <hch@infradead.org>
To: David Chinner <dgc@sgi.com>
Cc: xfs-dev@sgi.com, xfs@oss.sgi.com
Subject: Re: Review: fix block reservation to work with per-cpu counters
Date: Mon, 8 Jan 2007 10:52:03 +0000 [thread overview]
Message-ID: <20070108105203.GA31252@infradead.org> (raw)
In-Reply-To: <20070108061040.GD44411608@melbourne.sgi.com>
On Mon, Jan 08, 2007 at 05:10:40PM +1100, David Chinner wrote:
> Currently, XFS_IOC_SET_RESBLKS will not work properly when
> per-cpu superblock counters are enabled. Reservations can be lost
> silently as they are applied to the incore superblock instead of
> the currently active counters.
>
> Rather than try to shoe-horn the current reservation code into
> the per-cpu counters or vice-versa, we lock the superblock
> and snap the current counter state and work on that number.
> Once we work out exactly how much we need to "allocate" to
> the reserved area, we drop the lock and call xfs_mod_incore_sb()
> which will do all the right things w.r.t to the counter state.
>
> If we fail to get as much as we want (i.e. ENOSPC is returned)
> we go back to the start and try to allocate as much of what is
> left.
>
> Comments?
Sounds okay. Reservations shouldn't be frequent enough for this
to have a performance impact.
next prev parent reply other threads:[~2007-01-08 10:53 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-01-08 6:10 Review: fix block reservation to work with per-cpu counters David Chinner
2007-01-08 10:52 ` Christoph Hellwig [this message]
-- strict thread matches above, loose matches on Subject: below --
2007-01-15 21:31 Kevin Jamieson
2007-01-15 23:47 ` David Chinner
2007-01-16 12:06 ` David Chatterton
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