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Old 11-19-2006, 08:36 AM   #1
gwiesenekker
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Registered: Oct 2005
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HPET example


Hi,

I am looking for a replacement of the RDTSC instruction as it is no longer useful on the newer multi-core and power-saving CPU's.
The High Precision Event Timer (HPET) seems to a suitable candidate, but I cannot find good coumentation on how to use the API.
I have found an example C program in the kernel documentation, but it does tell how to use it. You have to specify a device name, but which? I have a '/dev/hpet' device on Fedora Core 6, but open() fails on it.

How can you find out if the BIOS supports HPET?
Where can I find good documentation or an example program that shows how to get a RDTSC counter using HPET?


Regards,
Gijsbert
 
Old 11-19-2006, 09:27 AM   #2
jschiwal
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There is an hpet.txt file in the kernel source Documentation. Also, the hpet.c source refers to documentation at the intel site: http://www.intel.com/technology/arch...e/hpetspec.htm

A search on the Intel site shows up informaton as well, like this Q&A: http://softwareforums.intel.com/isn/.../30225022.aspx

This is probably old information to you. Here is some background information from Microsoft. Interestingly, XP doesn't offer support. Vista will. http://www.microsoft.com/whdc/system/CEC/mm-timer.mspx

It sounds like a hpet timer is detected during bootup using acpi. However, some bioses don't support it. Others like in a Dell Xeon server support it but have it disabled by default in the BIOS settings.
 
  


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