From mboxrd@z Thu Jan  1 00:00:00 1970
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Date: Fri, 03 Feb 2006 10:26:36 +0100
From: Jan Kiszka <jan.kiszka@domain.hid>
MIME-Version: 1.0
Subject: Re: [Xenomai-core] some results on my laptop
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To: Anders Blomdell <anders.blomdell@domain.hid>
Cc: xenomai@xenomai.org

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Anders Blomdell wrote:
> 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, woul=
d
>>> 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 o=
f
>> 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 H=
z).
>=20

Great. Someone should go out and choke a few hardware developers again
for being that short-sighted. So the PM timer is the most robust one,
just a bit slow.

Jan


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