RE: Ext3 layout and I/O performace

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Can any one tell me ....what WEAK-MODULES exactly is ?

Is this supported in AS4U5 or AS4U6....

Thanks & Regards,
Saquib Imam

-----Original Message-----
From: kernelnewbies-bounce@xxxxxxxxxxxx
[mailto:kernelnewbies-bounce@xxxxxxxxxxxx] On Behalf Of Thomas Petazzoni
Sent: Thursday, December 27, 2007 7:27 PM
To: kernelnewbies@xxxxxxxxxxxx
Subject: Re: Ext3 layout and I/O performace

Le Thu, 27 Dec 2007 16:23:14 +0800,
"Wang Yu" <wangyuict@xxxxxxxxx> a écrit :

> 1.Why the performances under different subdirs varies so much? for
> example in /mnt/test/0 the performance is 72/80, while in /mnt/test/1
> the performance is 49/53

I didn't had a precise look at your numbers, but there's one factor
that can explain this performance variation: the read/write performance
of an hard disk is not homogenous. The beginning of the disk is stored
on the further cylinders from the center, while the end of the disk is
stored on the cylinders close to the center. Because the disk rotation
speed is constant, and the information density is constant, the raw
performance of the disk is not the same for all cylinders. The
performance degradation can be up to 50% when comparing performances at
the beginning of the disk and at the end of the disk.

Sincerly,

Thomas
-- 
Thomas Petazzoni, thomas.petazzoni@xxxxxxxx, http://thomas.enix.org
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