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Message-ID: <4A37DA2C.8020106@gmail.com>
Date: Tue, 16 Jun 2009 10:45:16 -0700
From: Richard Henderson <rth7680@gmail.com>
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To: john stultz <johnstul@us.ibm.com>
CC: ink@jurassic.park.msu.ru, lkml <linux-kernel@vger.kernel.org>,
       linux-alpha@vger.kernel.org
Subject: Re: [PATCH] Convert alpha to use arch_gettimeoffset()
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john stultz wrote:
> On Fri, 2009-06-12 at 00:03 -0700, Richard Henderson wrote:
>   
>> john stultz wrote:
>>     
>>> I suspect the alpha arch could even be further improved to provide and
>>> rpcc() based clocksource, but not having the hardware, I don't feel
>>> comfortable attempting the more complicated conversion (but I'd be glad
>>> to help if anyone else is interested).
>>>       
>> Unfortunately this isn't possible.  The rpcc value is only 32-bits wide,
>> and so rolls over in approx 3 to 4 seconds.  Thus all the contortions to
>> try and use the truncated value for sub 1 second adjustments.
>>     
>
> That's actually ok. The ACPI PM clocksource on x86 is only 24 bits wide
> and wraps every 5 seconds. The generic timekeeping code handles the
> wrapping and accumulation for you.
>   
Interesting.
> Might you create a patch that does this conversion and apply it on top
> of mine? 
Unfortunately I don't have working hardware anymore.  Perhaps Ivan will 
be able to help here.


r~
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