From: Andrew Morton <akpm@zip.com.au>
To: Pavel Machek <pavel@ucw.cz>
Cc: kernel list <linux-kernel@vger.kernel.org>
Subject: Re: Sync over loop devices takes ages? [2.4.17]
Date: Thu, 28 Feb 2002 10:05:34 -0800 [thread overview]
Message-ID: <3C7E716E.9DC59B12@zip.com.au> (raw)
In-Reply-To: <20020228095955.GH774@elf.ucw.cz>
Pavel Machek wrote:
>
> Hi!
>
> I have a script (attached). At one point it tries to do sync... That
> sync take a long time, with disk mostly unused.
When doing (say) ext2-on-loop-on-ext2 you should always ensure
that the blocksize for the topmost filesystem is the same as
the one underneath. So probably you wanted `mkfs.ext2 -b 4096'.
If you have a 1k blocksize filesystem loop-mounted on a 4k blocksize
filesystem, every write of a 1k block requires a read of the underlying
4k block. Which is excrutiatingly slow.
Some readahead in the loop driver would help heaps.
-
next prev parent reply other threads:[~2002-02-28 18:12 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-02-28 9:59 Sync over loop devices takes ages? [2.4.17] Pavel Machek
2002-02-28 11:52 ` Bjorn Wesen
2002-02-28 18:05 ` Andrew Morton [this message]
2002-02-28 20:12 ` Pavel Machek
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