From owner-freebsd-current@FreeBSD.ORG  Tue Apr 26 10:37:41 2011
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Date: Tue, 26 Apr 2011 10:37:41 +0000
From: Alexander Best <arundel@freebsd.org>
To: Steve Wills <swills@FreeBSD.org>
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Subject: Re: responsiveness during IO tasks
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On Mon Apr 25 11, Steve Wills wrote:
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> Hash: SHA1
> 
> Hi,
> 
> I've noticed lately that when doing heavy IO, my 9-CURRENT system (Fri
> Apr 15 23:33:46 EDT 2011) is quite unresponsive. I have two ZFS mirrors
> setup and run KDE4. The system has 12GB of RAM.
> 
> When I, for example, copy an ISO image from one mirror to the other, the
> whole desktop becomes really slow during the copy. It takes a good 15
> seconds to open a new tab in Konsole, switching windows takes a while,
> etc. Once the copy is finished, things are fine. It wasn't like this
> back before I upgraded from 8.2-RC1 to 9-CURRENT. Has anyone else
> noticed something similar, or is it just me? Is there any other info I
> can provide or something I should look for?

i've noticed this too. for me the situation is sometimes even worse. during
heavy i/o the mouse cursor won't even respond.

i think this is a scheduler isse. maybe running a non-preemptive kernel or
switching to the old 4bsd scheduler fixes it?

cheers.
alex

> 
> Thanks,
> Steve
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-- 
a13x