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From: Jeff Layton <jlayton@redhat.com>
To: Christoph Hellwig <hch@infradead.org>
Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-nfs@vger.kernel.org, linux-ext4@vger.kernel.org,
	linux-btrfs@vger.kernel.org, linux-xfs@vger.kernel.org
Subject: Re: [RFC PATCH v1 00/30] fs: inode->i_version rework and optimization
Date: Thu, 22 Dec 2016 09:42:04 -0500	[thread overview]
Message-ID: <1482417724.3924.39.camel@redhat.com> (raw)
In-Reply-To: <20161222084549.GA8833@infradead.org>

On Thu, 2016-12-22 at 00:45 -0800, Christoph Hellwig wrote:
> On Wed, Dec 21, 2016 at 12:03:17PM -0500, Jeff Layton wrote:
> > 
> > Only btrfs, ext4, and xfs implement it for data changes. Because of
> > this, these filesystems must log the inode to disk whenever the
> > i_version counter changes. That has a non-zero performance impact,
> > especially on write-heavy workloads, because we end up dirtying the
> > inode metadata on every write, not just when the times change. [1]
> 
> Do you have numbers to justify these changes?

I have numbers. As to whether they justify the changes, I'm not sure.
This helps a lot on a (admittedly nonsensical) 1-byte write workload. On
XFS, with this fio jobfile:

--------------------8<------------------
[global]
direct=0
size=2g
filesize=512m
bsrange=1-1
timeout=60
numjobs=1
directory=/mnt/scratch

[f1]
filename=randwrite
rw=randwrite
--------------------8<------------------

Unpatched kernel:
  WRITE: io=7707KB, aggrb=128KB/s, minb=128KB/s, maxb=128KB/s, mint=60000msec, maxt=60000msec

Patched kernel:
  WRITE: io=12701KB, aggrb=211KB/s, minb=211KB/s, maxb=211KB/s, mint=60000msec, maxt=60000msec

So quite a difference there and it's pretty consistent across runs. If I
change the jobfile to have "direct=1" and "bsrange=4k-4k", then any
variation between the two doesn't seem to be significant (numbers vary
as much between runs on the same kernels and are roughly the same).

Playing with buffered I/O sizes between 1 byte and 4k shows that as the
I/O sizes get larger, this makes less difference (which is what I'd
expect).

Previous testing with ext4 shows roughly the same results. btrfs shows
some benefit here but significantly less than with ext4 or xfs. Not sure
why that is yet -- maybe CoW effects?

That said, I don't have a great test rig for this. I'm using VMs with a
dedicated LVM volume that's on a random SSD I had laying around. It
could use testing on a wider set of configurations and workloads.

I was also hoping that others may have workloads that they think might
be (postively or negatively) affected by these changes. If you can think
of any in particular, then I'm interested to hear about them.

-- 
Jeff Layton <jlayton@redhat.com>

  reply	other threads:[~2016-12-22 14:42 UTC|newest]

Thread overview: 87+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-12-21 17:03 Jeff Layton
2016-12-21 17:03 ` [RFC PATCH v1 01/30] lustre: don't set f_version in ll_readdir Jeff Layton
2016-12-21 17:03 ` [RFC PATCH v1 02/30] ecryptfs: remove unnecessary i_version bump Jeff Layton
2016-12-21 17:03 ` [RFC PATCH v1 03/30] ceph: remove the bump of i_version Jeff Layton
2016-12-21 17:03 ` [RFC PATCH v1 04/30] f2fs: don't bother setting i_version Jeff Layton
2016-12-21 17:03 ` [RFC PATCH v1 05/30] hpfs: don't bother with the i_version counter Jeff Layton
2016-12-21 17:03 ` [RFC PATCH v1 06/30] jfs: remove initialization of " Jeff Layton
2016-12-21 17:03 ` [RFC PATCH v1 07/30] nilfs2: remove inode->i_version initialization Jeff Layton
2016-12-21 17:03 ` [RFC PATCH v1 08/30] orangefs: remove initialization of i_version Jeff Layton
2016-12-21 17:03 ` [RFC PATCH v1 09/30] reiserfs: remove unneeded i_version bump Jeff Layton
2016-12-21 17:03 ` [RFC PATCH v1 10/30] ntfs: remove i_version handling Jeff Layton
2016-12-21 17:03 ` [RFC PATCH v1 11/30] fs: new API for handling i_version Jeff Layton
2017-03-03 22:36   ` J. Bruce Fields
2017-03-04  0:09     ` Jeff Layton
2017-03-03 23:55   ` NeilBrown
2017-03-04  1:58     ` Jeff Layton
2016-12-21 17:03 ` [RFC PATCH v1 12/30] fat: convert to new i_version API Jeff Layton
2016-12-21 17:03 ` [RFC PATCH v1 13/30] affs: " Jeff Layton
2016-12-21 17:03 ` [RFC PATCH v1 14/30] afs: " Jeff Layton
2016-12-21 17:03 ` [RFC PATCH v1 15/30] btrfs: " Jeff Layton
2016-12-21 17:03 ` [RFC PATCH v1 16/30] exofs: switch " Jeff Layton
2016-12-21 17:03 ` [RFC PATCH v1 17/30] ext2: convert " Jeff Layton
2016-12-21 17:03 ` [RFC PATCH v1 18/30] ext4: " Jeff Layton
2016-12-21 17:03 ` [RFC PATCH v1 19/30] nfs: " Jeff Layton
2016-12-21 17:03 ` [RFC PATCH v1 20/30] nfsd: " Jeff Layton
2016-12-21 17:03 ` [RFC PATCH v1 21/30] ocfs2: " Jeff Layton
2016-12-21 17:03 ` [RFC PATCH v1 22/30] ufs: use " Jeff Layton
2016-12-21 17:03 ` [RFC PATCH v1 23/30] xfs: convert to " Jeff Layton
2016-12-21 17:03 ` [RFC PATCH v1 24/30] IMA: switch IMA over " Jeff Layton
2016-12-21 17:03 ` [RFC PATCH v1 25/30] fs: add a "force" parameter to inode_inc_iversion Jeff Layton
2016-12-21 17:03 ` [RFC PATCH v1 26/30] fs: only set S_VERSION when updating times if it has been queried Jeff Layton
2016-12-21 17:03 ` [RFC PATCH v1 27/30] xfs: avoid setting XFS_ILOG_CORE if i_version doesn't need incrementing Jeff Layton
2016-12-21 17:03 ` [RFC PATCH v1 28/30] btrfs: only dirty the inode in btrfs_update_time if something was changed Jeff Layton
2016-12-21 17:03 ` [RFC PATCH v1 29/30] fs: track whether the i_version has been queried with an i_state flag Jeff Layton
2017-03-04  0:03   ` NeilBrown
2017-03-04  0:43     ` Jeff Layton
2016-12-21 17:03 ` [RFC PATCH v1 30/30] fs: convert i_version counter over to an atomic64_t Jeff Layton
2016-12-22  8:38   ` Amir Goldstein
2016-12-22 13:27     ` Jeff Layton
2017-03-04  0:00   ` NeilBrown
2016-12-22  8:45 ` [RFC PATCH v1 00/30] fs: inode->i_version rework and optimization Christoph Hellwig
2016-12-22 14:42   ` Jeff Layton [this message]
2017-03-20 21:43     ` J. Bruce Fields
2017-03-21 13:45       ` Christoph Hellwig
2017-03-21 16:30         ` J. Bruce Fields
2017-03-21 17:23           ` Jeff Layton
2017-03-21 17:37             ` J. Bruce Fields
2017-03-21 17:51               ` J. Bruce Fields
2017-03-21 18:30             ` J. Bruce Fields
2017-03-21 18:46               ` Jeff Layton
2017-03-21 19:13                 ` J. Bruce Fields
2017-03-21 21:54                   ` Jeff Layton
2017-03-29 11:15                 ` Jan Kara
2017-03-29 17:54                   ` Jeff Layton
2017-03-29 23:41                     ` Dave Chinner
2017-03-30 11:24                       ` Jeff Layton
2017-04-04 18:38                       ` J. Bruce Fields
2017-03-30  6:47                     ` Jan Kara
2017-03-30 11:11                       ` Jeff Layton
2017-03-30 16:12                         ` J. Bruce Fields
2017-03-30 18:35                           ` Jeff Layton
2017-03-30 21:11                             ` Boaz Harrosh
2017-04-04 18:31                             ` J. Bruce Fields
2017-04-05  1:43                               ` NeilBrown
2017-04-05  8:05                                 ` Jan Kara
2017-04-05 18:14                                   ` J. Bruce Fields
2017-05-11 18:59                                     ` J. Bruce Fields
2017-05-11 22:22                                       ` NeilBrown
2017-05-12 16:21                                         ` J. Bruce Fields
2017-10-30 13:21                                           ` Jeff Layton
2017-05-12  8:27                                       ` Jan Kara
2017-05-12 15:56                                         ` J. Bruce Fields
2017-05-12 11:01                                       ` Jeff Layton
2017-05-12 15:57                                         ` J. Bruce Fields
2017-04-06  1:12                                   ` NeilBrown
2017-04-06  7:22                                     ` Jan Kara
2017-04-05 17:26                                 ` J. Bruce Fields
2017-04-01 23:05                           ` Dave Chinner
2017-04-03 14:00                             ` Jan Kara
2017-04-04 12:34                               ` Dave Chinner
2017-04-04 17:53                                 ` J. Bruce Fields
2017-04-05  1:26                                 ` NeilBrown
2017-03-21 21:45             ` Dave Chinner
2017-03-22 19:53               ` Jeff Layton
2017-03-03 23:00 ` J. Bruce Fields
2017-03-04  0:53   ` Jeff Layton
2017-03-08 17:29     ` J. Bruce Fields

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