From: David Brown <david@westcontrol.com>
To: linux-btrfs@vger.kernel.org
Subject: Re: Confused by performance
Date: Thu, 17 Jun 2010 08:57:01 +0200 [thread overview]
Message-ID: <hvch0f$jme$1@dough.gmane.org> (raw)
In-Reply-To: <AANLkTimKGCk7KlD4KQ8oXhnnOf0pj3VzzDmzzBIK0bNn@mail.gmail.com>
On 16/06/2010 21:35, Freddie Cash wrote:
> <snip a lot of fancy math that missed the point>
>
> That's all well and good, but you missed the part where he said ext2
> on a 5-way LVM stripeset is many times faster than btrfs on a 5-way
> btrfs stripeset.
>
> IOW, same 5-way stripeset, different filesystems and volume managers,
> and very different performance.
>
> And he's wondering why the btrfs method used for striping is so much
> slower than the lvm method used for striping.
>
This could easily be explained by Roberto's theory and maths - if the
lvm stripe set used large stripe sizes so that the random reads were
mostly read from a single disk, it would be fast. If the btrfs stripes
were small, then it would be slow due to all the extra seeks.
Do we know anything about the stripe sizes used?
next prev parent reply other threads:[~2010-06-17 6:57 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-05-24 21:08 Confused by performance K. Richard Pixley
2010-05-25 3:59 ` Mike Fedyk
2010-05-28 1:45 ` K. Richard Pixley
2010-06-16 18:08 ` K. Richard Pixley
2010-06-16 19:21 ` Roberto Ragusa
[not found] ` <AANLkTinM6ab_KEynfgvVT9v5TmcogoLZ0PLAz2oPnsiS@mail.gmail.com>
2010-06-16 19:35 ` Freddie Cash
2010-06-16 19:56 ` Roberto Ragusa
2010-06-17 6:57 ` David Brown [this message]
2010-06-16 21:44 ` Daniel J Blueman
2010-06-17 9:57 ` Chris Mason
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