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From: Andi Kleen <andi@firstfloor.org>
To: Yannis Klonatos <klonatos@ics.forth.gr>
Cc: xfs@oss.sgi.com
Subject: Re: XFS peculiar behavior
Date: Wed, 23 Jun 2010 12:24:27 +0200	[thread overview]
Message-ID: <87bpb2avxg.fsf@basil.nowhere.org> (raw)
In-Reply-To: <4C21B9AF.9010307@ics.forth.gr> (Yannis Klonatos's message of "Wed, 23 Jun 2010 10:37:19 +0300")

Yannis Klonatos <klonatos@ics.forth.gr> writes:

>         The problem is that i have noticed that XFS may - not all

Why is that a problem?

> times - split a table over a large disk distance. For
> example in one run i have noticed that a file of 13GByte is split over
> a 4,7TByte distance (I calculate this distance
> by subtracting the final block used for the file with the first
> one. The two disk blocks values are acquired using the
> FIBMAP ioctl).

I don't know if it's the only reason, but XFS does a lot of data
structure locking and updates per allocation group, so spreading
to multiple AGs gives better scalability to many CPUs.

Also I suppose it's good to avoid hot spots on the underlying 
device.

-Andi
-- 
ak@linux.intel.com -- Speaking for myself only.

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  parent reply	other threads:[~2010-06-23 10:21 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-06-23  7:37 XFS peculiar behavior Yannis Klonatos
2010-06-23 10:16 ` Michael Monnerie
2010-06-23 10:24 ` Andi Kleen [this message]
2010-06-23 15:04   ` Michael Monnerie
2010-06-23 16:21 ` Eric Sandeen
2010-06-23 23:17 ` Dave Chinner
2010-06-24 14:11   ` Yannis Klonatos
2010-06-24 15:21     ` Eric Sandeen
2010-06-24 15:35       ` Yannis Klonatos
2010-06-25  0:58         ` Dave Chinner
2010-06-25  0:46       ` Dave Chinner

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