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Date:      Tue, 30 Oct 2012 22:41:04 +1030
From:      Shane Ambler <FreeBSD@ShaneWare.Biz>
To:        Andriy Gapon <avg@FreeBSD.org>
Cc:        Steven Nikkel <steven_nikkel@ertyu.org>, freebsd-stable@FreeBSD.org
Subject:   Re: CPU Competition Issue
Message-ID:  <508FC3D8.8030800@ShaneWare.Biz>
In-Reply-To: <508F9671.3060501@FreeBSD.org>
References:  <M.O.0.1210292022200.70211@ertyu.org> <508F9671.3060501@FreeBSD.org>

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On 30/10/2012 19:27, Andriy Gapon wrote:
> on 30/10/2012 03:33 Steven Nikkel said the following:
>> I'm running a long duration CPU-centric process that will gobble up all
>> available CPU time. I have it set to run at nice +20. While it's running I've
>> noticed other processes have a hard time getting CPU time and run their
>> activites very slowly. The processes I've noticed issues with are IO involved,
>> but they don't appear to be IO blocked as they run dramatically faster and use
>> much more CPU time when the CPU intensive process is not running. I haven't
>> noticed issues with other processes, but I haven't been looking. If I push my
>> CPU intensive process into idle priority 1, all the other processes return to
>> their normal behaviour as if it's not running.
>>
>> This seems to be a specific behaviour on this one machine running 9.0-RELEASE-p4
>> on an Atom 330 dual core. I've tried with and without hyperthreading enabled
>> with no noticeable change in behaviour.
>
> Can you try with lower nice value, like +10?
> You want a fix from r228718.  AFAIR, it is not in 9.0.
>

Could it be cache based? The atom's smaller cache causing more cache misses.

Would you be running zfs?




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