HPET vs other timers

Kris Kennaway kris at obsecurity.org
Sat Jun 2 21:31:47 UTC 2007


On Sat, Jun 02, 2007 at 09:15:13PM +0000, Poul-Henning Kamp wrote:
> In message <20070602194151.GA1604 at rot13.obsecurity.org>, Kris Kennaway writes:
^^^
JFYI, I didn't :-)

> 
> >> Anyone able to speculate why though?  HPET only reads 32 bits from a
> >> memory mapped region.  No locking or other requirements.  ACPI_timer
> >> does multiple IO ops, which according to bde@ are much slower than
> >> memory reads.  
> 
> HPET needs to do metastability mitigation and is not "just a read
> from a memory mapped region".
> 
> -- 
> Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
> phk at FreeBSD.ORG         | TCP/IP since RFC 956
> FreeBSD committer       | BSD since 4.3-tahoe    
> Never attribute to malice what can adequately be explained by incompetence.
> 


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