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Date: Fri, 03 Feb 2006 10:18:24 +0100
From: Anders Blomdell <anders.blomdell@domain.hid>
MIME-Version: 1.0
Subject: Re: [Xenomai-core] some results on my laptop
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To: Jan Kiszka <jan.kiszka@domain.hid>
Cc: xenomai@xenomai.org

Jan Kiszka wrote:
> Jan Kiszka wrote:
> 
>>...
>>What about other time sources on x86? Which systems already have HPET
>>these days, and does this source not suffer from frequency scaling? I
>>once read that HPET is quite easy to program, is this true? IOW, would
>>it be worth considering to add this to the HAL?
> 
> 
> There are actually only few registers:
> 
> http://www.intel.com/hardwaredesign/hpetspec_1.pdf
> 
> Even a replacement for the TSC is available ("Main Counter"), but I
> guess that some effort will be required to replace all direct usages of
> rdtsc in the current Xenomai code, right?
And unfortunately they aren't guaranteed to survive S3 sleep, which laptops 
spend a lot of time in (around 50% when doing coantrol at 100 Hz).

-- 
Anders