Date: Thu, 17 May 2007 12:34:36 +0200
From: DervishD <lkml@dervishd.net>
To: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: usb-storage nice value
Message-ID: <20070517103436.GA15329@DervishD>
Mail-Followup-To: Alan Cox <alan@lxorguk.ukuu.org.uk>,
	Linux-kernel <linux-kernel@vger.kernel.org>
References: <20070517100308.GA14667@DervishD> <20070517111901.202309d9@the-village.bc.nu>
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    Hi Alan :)

 * Alan Cox <alan@lxorguk.ukuu.org.uk> dixit:
> >     My system is a bit modest: a 7 years old motheboard with VIA686B, a
> > 1900+ Athlon XP, but with plenty of RAM (1280MB + 1GB swap). I know, if
> > I want more hard disk performance I should buy a new box with SATA or
> > whatever, but the fact is that I hadn't problems with the same hardware
> > and kernel 2.4.x. I need 2.6.x, so I cannot go back to 2.4.x.
> 
> Disk is actually less likely to be a problem than PCI bus bandwidth - the
> older VIA boards seem quite happy to fill the PCI bus solid during bursts
> of disk I/O

    I was supposing something in that line, since disk speed is quite
high (when I only read or write but not both). I just didn't think about
PCI bandwidth.

> > bad idea too, where should I look for culprits so I can tweak the system
> > a bit and improve disk performance? I'm not 100% sure that the problem
> 
> You might want to try the reverse if you have a UDMA100 or UDMA133 drive
> then setting the speed down to UDMA66 definitely evens out the behaviour
> of VIA boards when doing video capture. I don't know if it helps playback.

    Won't that reduce disk performance when using just one disk? I don't
pass much data between disks (or even copy data within one disk), so not
being able to watch movies while copying data is, for me, more
acceptable than having a slower disk all the time.

    And yes, all my disks are UDMA100.

    Is there a way of changing chipset behaviour from userspace so PCI
bus is not filled during IO bursts?

    Thanks a lot for your answer, Alan :)

    Ra?l N??ez de Arenas Coronado

-- 
Linux Registered User 88736 | http://www.dervishd.net
It's my PC and I'll cry if I want to... RAmen!
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