From: Alexander Larsson <alexl@redhat.com>
To: Gao Xiang <hsiangkao@linux.alibaba.com>,
Amir Goldstein <amir73il@gmail.com>
Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
gscrivan@redhat.com, david@fromorbit.com, brauner@kernel.org,
viro@zeniv.linux.org.uk, Vivek Goyal <vgoyal@redhat.com>,
Miklos Szeredi <miklos@szeredi.hu>
Subject: Re: [PATCH v3 0/6] Composefs: an opportunistically sharing verified image filesystem
Date: Wed, 25 Jan 2023 11:15:59 +0100 [thread overview]
Message-ID: <2ef122849d6f35712b56ffbcc95805672980e185.camel@redhat.com> (raw)
In-Reply-To: <e840d413-c1a7-d047-1a63-468b42571846@linux.alibaba.com>
On Wed, 2023-01-25 at 18:05 +0800, Gao Xiang wrote:
>
>
> On 2023/1/25 17:37, Alexander Larsson wrote:
> > On Tue, 2023-01-24 at 21:06 +0200, Amir Goldstein wrote:
> > > On Tue, Jan 24, 2023 at 3:13 PM Alexander Larsson
> > > <alexl@redhat.com>
>
> ...
>
> > > >
> > > > They are all strictly worse than squashfs in the above testing.
> > > >
> > >
> > > It's interesting to know why and if an optimized mkfs.erofs
> > > mkfs.ext4 would have done any improvement.
> >
> > Even the non-loopback mounted (direct xfs backed) version performed
> > worse than the squashfs one. I'm sure a erofs with sparse files
> > would
> > do better due to a more compact file, but I don't really see how it
> > would perform significantly different than the squashfs code. Yes,
> > squashfs lookup is linear in directory length, while erofs is
> > log(n),
> > but the directories are not so huge that this would dominate the
> > runtime.
> >
> > To get an estimate of this I made a broken version of the erofs
> > image,
> > where the metacopy files are actually 0 byte size rather than
> > sparse.
> > This made the erofs file 18M instead, and gained 10% in the cold
> > cache
> > case. This, while good, is not near enough to matter compared to
> > the
> > others.
> >
> > I don't think the base performance here is really much dependent on
> > the
> > backing filesystem. An ls -lR workload is just a measurement of the
> > actual (i.e. non-dcache) performance of the filesystem
> > implementation
> > of lookup and iterate, and overlayfs just has more work to do here,
> > especially in terms of the amount of i/o needed.
>
> I will form a formal mkfs.erofs version in one or two days since
> we're
> cerebrating Lunar New year now.
>
> Since you don't have more I/O traces for analysis, I have to do
> another
> wild guess.
>
> Could you help benchmark your v2 too? I'm not sure if such
> performance also exists in v2. The reason why I guess as this is
> that it seems that you read all dir inode pages when doing the first
> lookup, it can benefit to seq dir access.
>
> I'm not sure if EROFS can make a similar number by doing forcing
> readahead on dirs to read all dir data at once as well.
>
> Apart from that I don't see significant difference, at least
> personally
> I'd like to know where it could have such huge difference. I don't
> think that is all because of read-only on-disk format differnce.
I think the performance difference between v2 and v3 would be rather
minor in this case, because I don't think a lot of the directories are
large enough to be split in chunks. I also don't believe erofs and
composefs should fundamentally differ much in performance here, given
that both use a compact binary searchable layout for dirents. However,
the full comparison is "composefs" vs "overlayfs + erofs", and in that
case composefs wins.
--
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
=-=-=
Alexander Larsson Red Hat,
Inc
alexl@redhat.com alexander.larsson@gmail.com
He's an obese Catholic messiah who knows the secret of the alien
invasion. She's a provocative Bolivian single mother living on borrowed
time. They fight crime!
next prev parent reply other threads:[~2023-01-25 10:17 UTC|newest]
Thread overview: 80+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-20 15:23 [PATCH v3 0/6] Composefs: an opportunistically sharing verified image filesystem Alexander Larsson
2023-01-20 15:23 ` [PATCH v3 1/6] fsverity: Export fsverity_get_digest Alexander Larsson
2023-01-20 15:23 ` [PATCH v3 2/6] composefs: Add on-disk layout header Alexander Larsson
2023-01-20 15:23 ` [PATCH v3 3/6] composefs: Add descriptor parsing code Alexander Larsson
2023-01-20 15:23 ` [PATCH v3 4/6] composefs: Add filesystem implementation Alexander Larsson
2023-01-20 15:23 ` [PATCH v3 5/6] composefs: Add documentation Alexander Larsson
2023-01-21 2:19 ` Bagas Sanjaya
2023-01-20 15:23 ` [PATCH v3 6/6] composefs: Add kconfig and build support Alexander Larsson
2023-01-20 19:44 ` [PATCH v3 0/6] Composefs: an opportunistically sharing verified image filesystem Amir Goldstein
2023-01-20 22:18 ` Giuseppe Scrivano
2023-01-21 3:08 ` Gao Xiang
2023-01-21 16:19 ` Giuseppe Scrivano
2023-01-21 17:15 ` Gao Xiang
2023-01-21 22:34 ` Giuseppe Scrivano
2023-01-22 0:39 ` Gao Xiang
2023-01-22 9:01 ` Giuseppe Scrivano
2023-01-22 9:32 ` Giuseppe Scrivano
2023-01-24 0:08 ` Gao Xiang
2023-01-21 10:57 ` Amir Goldstein
2023-01-21 15:01 ` Giuseppe Scrivano
2023-01-21 15:54 ` Amir Goldstein
2023-01-21 16:26 ` Gao Xiang
2023-01-23 17:56 ` Alexander Larsson
2023-01-23 23:59 ` Gao Xiang
2023-01-24 3:24 ` Amir Goldstein
2023-01-24 13:10 ` Alexander Larsson
2023-01-24 14:40 ` Gao Xiang
2023-01-24 19:06 ` Amir Goldstein
2023-01-25 4:18 ` Dave Chinner
2023-01-25 8:32 ` Amir Goldstein
2023-01-25 10:08 ` Alexander Larsson
2023-01-25 10:43 ` Amir Goldstein
2023-01-25 10:39 ` Giuseppe Scrivano
2023-01-25 11:17 ` Amir Goldstein
2023-01-25 12:30 ` Giuseppe Scrivano
2023-01-25 12:46 ` Amir Goldstein
2023-01-25 13:10 ` Giuseppe Scrivano
2023-01-25 18:07 ` Amir Goldstein
2023-01-25 19:45 ` Giuseppe Scrivano
2023-01-25 20:23 ` Amir Goldstein
2023-01-25 20:29 ` Amir Goldstein
2023-01-27 15:57 ` Vivek Goyal
2023-01-25 15:24 ` Christian Brauner
2023-01-25 16:05 ` Giuseppe Scrivano
2023-01-25 9:37 ` Alexander Larsson
2023-01-25 10:05 ` Gao Xiang
2023-01-25 10:15 ` Alexander Larsson [this message]
2023-01-27 10:24 ` Gao Xiang
2023-02-01 4:28 ` Jingbo Xu
2023-02-01 7:44 ` Amir Goldstein
2023-02-01 8:59 ` Jingbo Xu
2023-02-01 9:52 ` Alexander Larsson
2023-02-01 12:39 ` Jingbo Xu
2023-02-01 9:46 ` Alexander Larsson
2023-02-01 10:01 ` Gao Xiang
2023-02-01 11:22 ` Gao Xiang
2023-02-02 6:37 ` Amir Goldstein
2023-02-02 7:17 ` Gao Xiang
2023-02-02 7:37 ` Gao Xiang
2023-02-03 11:32 ` Alexander Larsson
2023-02-03 12:46 ` Amir Goldstein
2023-02-03 15:09 ` Gao Xiang
2023-02-05 19:06 ` Amir Goldstein
2023-02-06 7:59 ` Amir Goldstein
2023-02-06 10:35 ` Miklos Szeredi
2023-02-06 13:30 ` Amir Goldstein
2023-02-06 16:34 ` Miklos Szeredi
2023-02-06 17:16 ` Amir Goldstein
2023-02-06 18:17 ` Amir Goldstein
2023-02-06 19:32 ` Miklos Szeredi
2023-02-06 20:06 ` Amir Goldstein
2023-02-07 8:12 ` Alexander Larsson
2023-02-06 12:51 ` Alexander Larsson
2023-02-07 8:12 ` Jingbo Xu
2023-02-06 12:43 ` Alexander Larsson
2023-02-06 13:27 ` Gao Xiang
2023-02-06 15:31 ` Alexander Larsson
2023-02-01 12:06 ` Jingbo Xu
2023-02-02 4:57 ` Jingbo Xu
2023-02-02 4:59 ` Jingbo Xu
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