From: Dave Chinner <david@fromorbit.com>
To: Brian Foster <bfoster@redhat.com>
Cc: xfs@oss.sgi.com
Subject: Re: [RFC PATCH 2/2] xfs: sysfs attributes for the current log state
Date: Tue, 20 May 2014 07:56:58 +1000 [thread overview]
Message-ID: <20140519215658.GD8554@dastard> (raw)
In-Reply-To: <1400263966-35541-3-git-send-email-bfoster@redhat.com>
On Fri, May 16, 2014 at 02:12:46PM -0400, Brian Foster wrote:
> Create sysfs attributes to export the current runtime state of the log
> to userspace. Note that the filesystem should be frozen for best
> accuracy/consistency when reading these values, but is not required.
> This is for testing and debug purposes only.
>
> Create the following per-mount attributes: log_head_lsn, log_tail_lsn,
> reserve_head_lsn and write_head_lsn. These represent the physical log
Reserve and write heads are not log sequence numbers (LSNs). A LSN
is a cycle:block count tuple, while a grant head is a cycle:byte
count tuple....
Calling the reserve_grant_head/write_grant_head would make more
sense, I think, as would splitting them into cycle/byte output
pairs. Splitting them make sense because if we increase the log size
beyond 2GB we're going to need a different in-memory representation
for the grant heads (i.e. need more than 32 bits for byte count), so
we should probably handle that up front in the sysfs API...
Cheers,
Dave.
--
Dave Chinner
david@fromorbit.com
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next prev parent reply other threads:[~2014-05-19 21:57 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-05-16 18:12 [RFC PATCH 0/2] xfs: sysfs attribute support Brian Foster
2014-05-16 18:12 ` [RFC PATCH 1/2] xfs: add basic per-mount " Brian Foster
2014-05-20 12:16 ` Dave Chinner
2014-05-16 18:12 ` [RFC PATCH 2/2] xfs: sysfs attributes for the current log state Brian Foster
2014-05-19 21:56 ` Dave Chinner [this message]
2014-05-20 11:17 ` Brian Foster
2014-05-20 11:52 ` Dave Chinner
2014-05-21 14:48 ` [RFC PATCH 0/2] xfs: sysfs attribute support Christoph Hellwig
2014-05-22 13:16 ` Brian Foster
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