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From: "Darrick J. Wong" <djwong@kernel.org>
To: Dave Chinner <david@fromorbit.com>
Cc: Brian Foster <bfoster@redhat.com>,
	linux-xfs@vger.kernel.org, hch@infradead.org
Subject: Re: [PATCH 5/9] xfs: force inode garbage collection before fallocate when space is low
Date: Tue, 8 Jun 2021 17:25:41 -0700	[thread overview]
Message-ID: <20210609002541.GU2945738@locust> (raw)
In-Reply-To: <20210608215542.GL664593@dread.disaster.area>

On Wed, Jun 09, 2021 at 07:55:42AM +1000, Dave Chinner wrote:
> On Tue, Jun 08, 2021 at 08:32:04AM -0700, Darrick J. Wong wrote:
> > On Tue, Jun 08, 2021 at 07:48:05AM -0400, Brian Foster wrote:
> > > users/workloads that might operate under these conditions? I guess
> > > historically we've always recommended to not consistently operate in
> > > <20% free space conditions, so to some degree there is an expectation
> > > for less than optimal behavior if one decides to constantly bash an fs
> > > into ENOSPC. Then again with large enough files, will/can we put the
> > > filesystem into that state ourselves without any indication to the user?
> > > 
> > > I kind of wonder if unless/until there's some kind of efficient feedback
> > > between allocation and "pending" free space, whether deferred
> > > inactivation should be an optimization tied to some kind of heuristic
> > > that balances the amount of currently available free space against
> > > pending free space (but I've not combed through the code enough to grok
> > > whether this already does something like that).
> > 
> > Ooh!  You mentioned "efficient feedback", and one sprung immediately to
> > mind -- if the AG is near full (or above 80% full, or whatever) we
> > schedule the per-AG inodegc worker immediately instead of delaying it.
> 
> That's what the lowspace thresholds in speculative preallocation are
> for...
> 
> 20% of a 1TB AG is an awful lot of freespace still remaining, and
> if someone is asking for a 200GB fallocate(), they are always going
> to get some fragmentation on a used, 80% full filesystem regardless
> of deferred inode inactivation.
> 
> IMO, if you're going to do this, use the same thresholds we already
> use to limit preallocation near global ENOSPC and graduate it to be
> more severe the closer we get to global ENOSPC...

Ok.  I'll just crib the same 5/4/3/2/1% thresholds like prealloc, then.

--D

> 
> Cheers,
> 
> Dave.
> -- 
> Dave Chinner
> david@fromorbit.com

  reply	other threads:[~2021-06-09  0:25 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-07 22:24 [PATCHSET v6 0/9] xfs: deferred inode inactivation Darrick J. Wong
2021-06-07 22:24 ` [PATCH 1/9] xfs: refactor the inode recycling code Darrick J. Wong
2021-06-07 22:59   ` Dave Chinner
2021-06-08  0:14     ` Darrick J. Wong
2021-06-07 22:25 ` [PATCH 2/9] xfs: deferred inode inactivation Darrick J. Wong
2021-06-08  0:57   ` Dave Chinner
2021-06-08  4:40     ` Darrick J. Wong
2021-06-09  1:01       ` Dave Chinner
2021-06-09  1:28         ` Darrick J. Wong
2021-06-07 22:25 ` [PATCH 3/9] xfs: expose sysfs knob to control inode inactivation delay Darrick J. Wong
2021-06-08  1:09   ` Dave Chinner
2021-06-08  2:02     ` Darrick J. Wong
2021-06-07 22:25 ` [PATCH 4/9] xfs: force inode inactivation and retry fs writes when there isn't space Darrick J. Wong
2021-06-07 22:25 ` [PATCH 5/9] xfs: force inode garbage collection before fallocate when space is low Darrick J. Wong
2021-06-08  1:26   ` Dave Chinner
2021-06-08 11:48     ` Brian Foster
2021-06-08 15:32       ` Darrick J. Wong
2021-06-08 16:06         ` Brian Foster
2021-06-08 21:55         ` Dave Chinner
2021-06-09  0:25           ` Darrick J. Wong [this message]
2021-06-07 22:25 ` [PATCH 6/9] xfs: parallelize inode inactivation Darrick J. Wong
2021-06-07 22:25 ` [PATCH 7/9] xfs: create a polled function to force " Darrick J. Wong
2021-06-07 22:25 ` [PATCH 8/9] xfs: don't run speculative preallocation gc when fs is frozen Darrick J. Wong
2021-06-07 22:25 ` [PATCH 9/9] xfs: avoid buffer deadlocks when walking fs inodes Darrick J. Wong
  -- strict thread matches above, loose matches on Subject: below --
2021-03-26  0:21 [PATCHSET v5 0/9] xfs: deferred inode inactivation Darrick J. Wong
2021-03-26  0:22 ` [PATCH 5/9] xfs: force inode garbage collection before fallocate when space is low Darrick J. Wong

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