linux-ext4 - Re: Ext4 slow on links

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Message-ID: <20120621022818.GD9669@gamma.logic.tuwien.ac.at>
Date:	Thu, 21 Jun 2012 11:28:19 +0900
From:	Norbert Preining <preining@...ic.at>
To:	Eric Sandeen <sandeen@...hat.com>
Cc:	Ted Ts'o <tytso@....edu>,
	"linux-ext4@...r.kernel.org" <linux-ext4@...r.kernel.org>,
	Eric Sandeen <esandeen@...hat.com>
Subject: Re: Ext4 slow on links

Hi Eric,

thanks a lot for looking into that.

On Mi, 20 Jun 2012, Eric Sandeen wrote:
> so almost all reads, and no read merges; almost 35 megabytes read and every
> one was a small 4k IO.

Ouch, that hurts.

On Mi, 20 Jun 2012, Eric Sandeen wrote:
> Would you be willing to provide an "e2image -r" image of the filesystem?

Ok, it is running now since a few hours and I am far from finished
I guess, since there are 350+G on the fs, and the compressed image
is by now 200M.

Is it fine to do it on a running system, or do I have to boot
from USB or so?

If it is not toooo big I will tr to upload it to some place were
you can get access to.

On Mi, 20 Jun 2012, Eric Sandeen wrote:
> Oh, but Zach Brown reminds me that if we stat the entries in getdents/hash
> order, it's roughly random w.r.t. disk location.  Newer utils will sort into
> inode order, I think(?)  Might be interesting to strace the ls -l and see
> if it's doing it in inode order, or not.

Ok, is there a special option to strace, or -trace=all?

Best wishes

Norbert
------------------------------------------------------------------------
Norbert Preining            preining@...ist.ac.jp, logic.at, debian.org}
JAIST, Japan                                 TeX Live & Debian Developer
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