Re: [patch] remove unnecessary periodic superblock logging.

[David Chinner <dgc@sgi.com>]

On Thu, Apr 10, 2008 at 03:29:30PM +1000, Timothy Shimmin wrote:
> Barry Naujok wrote:
> >On Thu, 10 Apr 2008 14:20:01 +1000, David Chinner <dgc@sgi.com> wrote:
> >
> >>Remove periodic logging of in-core superblock counters.
> >>
> >>xfssyncd triggers the logging of superblock counters every
> >>30s if the filesystem is made with lazy-count=1. This will
> >>prevent disks from idling and spinning down as there will
> >>be a log write every 30s. With the way counter recovery
> >>works for lazy-count=1, this code is unnecessary and provides
> >>no real benefit, so just remove it.
> >
> >I'm happy with this (xfs_initialize_perag_data() does the
> >global counter recovery during mount).
> >
> 
> So we only do the sb count logging at unmount type times...
> xfs_attr_quiesce() and xfs_unmountfs(),
> when no log recovery will happen.
> Hmmm...so why do we have to log it out at these times?
> I'm forgetting how this works.

xfs_log_sbcount() sync's the incore counters to the superblock
buffer transactionally. Not strictly necessary, but for consistency
with other superblock updates.....

Cheers,

Dave.
-- 
Dave Chinner
Principal Engineer
SGI Australian Software Group