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From: Nicolas Boullis <nicolas.boullis@ecp.fr>
To: Jeff Dike <jdike@addtoit.com>,
	user-mode-linux-devel@lists.sourceforge.net
Subject: Re: [uml-devel] parallel I/O
Date: Mon, 06 Oct 2008 15:28:37 +0200	[thread overview]
Message-ID: <48EA1285.9050806@ecp.fr> (raw)
In-Reply-To: <20081004183731.cajymruq1vwocwks@webmail.ecp.fr>

Hi,

Nicolas Boullis wrote:
> On a reasonably new host, using as UBD devices logical volumes built  
> on top of a FC SAN, building a 10GB ext3 filesystem took something  
> like 50 seconds before my patch, and something like 3 seconds after  
> it. (I can check the exact values if you wish.)

Hmmm... my memory was making thing much better than they really are.
It's around 38 seconds with 2.6.18 (before the "batch I/O requests"
change); it's several minutes with unpatched 2.6.24, and it's around 7
seconds with patched 2.6.24...

To be more honnest, my patch contains a part similar to Steve
VanDeBogart's "ubd does multiple io's when one will suffice" patch.
Using 2.6.24 with his patch but still serialized I/O, the time is around
23 seconds.

Hence, my patch (with 16 threads per device) make things around 3 times
faster.


Cheers,

Nicolas Boullis
École Centrale Paris

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      reply	other threads:[~2008-10-06 13:31 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-09-12 13:40 [uml-devel] parallel I/O Nicolas Boullis
2008-09-15  8:59 ` Nicolas Boullis
2008-10-02 13:34   ` Nicolas Boullis
2008-10-04  4:28     ` Jeff Dike
2008-10-04 16:37       ` Nicolas Boullis
2008-10-06 13:28         ` Nicolas Boullis [this message]

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