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Date:      Tue, 30 May 2006 20:19:56 -0700
From:      Nate Lawson <nate@root.org>
To:        Andriy Gapon <avg@icyb.net.ua>
Cc:        freebsd-current@freebsd.org
Subject:   Re: Freeze due to performance_cx_lowest=LOW
Message-ID:  <447D0B5C.3020901@root.org>
In-Reply-To: <447C1BBD.5020004@icyb.net.ua>
References:  <1148837064.00534930.1148826605@10.7.7.3> <1148945069.00535906.1148934001@10.7.7.3> <447C1BBD.5020004@icyb.net.ua>

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Andriy Gapon wrote:
> on 29/05/2006 23:10 Nate Lawson said the following:
>> disable apic (hint.apic.0.disabled="1").  I isolated this a little while 
>> ago to the change to enable LAPIC timer.  However, there is currently no 
>> easy way to disable the LAPIC timer with APIC enabled so you have to 
>> disable APIC.  jhb@ and I have been discussing how to do this better but 
>> no easy answers apparently.
> 
> I am not sure what I am talking about, but is it potentially possible to
> drive timer system by more than one clock, actively using the most
> precise of them at any particular moment ? So that if LAPIC timer stops
> i8254 can be used instead.

That requires mixed mode delivery -- i8254 on legacy PIC irq and APIC 
mode for other interrupts.  jhb@ just killed this and isn't eager to add 
it back.  I'll let him explain if he has more to add.

-- 
Nate



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