From: Ted Ts'o <tytso@mit.edu>
To: Bernd Schubert <bernd.schubert@fastmail.fm>
Cc: Eric Sandeen <sandeen@redhat.com>,
Norbert Preining <preining@logic.at>,
"linux-ext4@vger.kernel.org" <linux-ext4@vger.kernel.org>
Subject: Re: Ext4 slow on links
Date: Fri, 22 Jun 2012 10:08:18 -0400 [thread overview]
Message-ID: <20120622140818.GA28155@thunk.org> (raw)
In-Reply-To: <4FE44089.2010609@fastmail.fm>
On Fri, Jun 22, 2012 at 11:53:13AM +0200, Bernd Schubert wrote:
> On 06/21/2012 06:05 AM, Eric Sandeen wrote:
> >On 6/20/12 9:28 PM, Norbert Preining wrote:
> >>Hi Eric,
> >>
> >
> >You could see if you could get this LD_PRELOAD working:
> >
> >http://git.kernel.org/?p=fs/ext2/e2fsprogs.git;a=blob_plain;f=contrib/spd_readdir.c
> >
>
> Hrmm, I need to look through that commit again, but on a first
> glance I cannot see code doing the sorting for ext3/ext4 only (e.g.
> by checking the fsid). So while I like the general approach, it will
> have the opposite effect for some file systems. I will report that
> back on the coreutils list.
>
> Thanks a lot for the pointer to the commit!
One warning about spd_readdir. It's not thread-safe, and I've noted
that some programs crash when they try using spd_readdir.so as a
pre-load. I've tried to fix some of the causes, and I think
thread-safety is the primary fix which is missing, but it's possible
that program which really care about telldir()/seekdir() behaviour as
it relates to readdir() and when files are added to a directory may
also end up getting surprised.
I wrote it primarily as a demonstration of how sorting by inode number
is a big win. It is *not* suitable for use in /etc/ld.so.preload!
If people want to try to make it safer, patches are accepted, but
ultimately it's better to fix this in the application; that way you
will get your performance gains no matter what OS you happen to be
running on, whether it's Linux, Solaris, AIX, OS X, etc.
- Ted
next prev parent reply other threads:[~2012-06-22 14:08 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-06-20 0:20 Ext4 slow on links Norbert Preining
2012-06-20 2:19 ` Ted Ts'o
2012-06-20 3:38 ` Norbert Preining
2012-06-20 3:57 ` Eric Sandeen
2012-06-20 4:01 ` Norbert Preining
2012-06-20 5:18 ` Norbert Preining
2012-06-20 14:07 ` Eric Sandeen
2012-06-20 19:35 ` Eric Sandeen
2012-06-21 2:28 ` Norbert Preining
2012-06-21 4:05 ` Eric Sandeen
2012-06-21 4:50 ` Norbert Preining
2012-06-21 5:18 ` Andreas Dilger
2012-06-21 6:55 ` Norbert Preining
2012-06-22 9:53 ` Bernd Schubert
2012-06-22 14:08 ` Ted Ts'o [this message]
2012-06-20 3:15 ` Eric Sandeen
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