John Baldwin wrote:
On Sunday 26 April 2009 10:27:42 pm Garrett Cooper wrote:
I'm seeing similar results.
[r...@orangebox /usr/home/gcooper]# dmesg | grep 'Timecounter "'
Timecounter "i8254" frequency 1193182 Hz quality 0
Timecounter "ACPI-fast" frequency 3579545 Hz quality 1000
Timecounter "HPET" frequency 14318180 Hz quality 900
[r...@orangebox /usr/home/gcooper]# ./cgt
1369355
[r...@orangebox /usr/home/gcooper]# sysctl
kern.timecounter.hardware="ACPI-fast"
kern.timecounter.hardware: HPET -> ACPI-fast
[r...@orangebox /usr/home/gcooper]# ./cgt
772289
Why's the default ACPI-fast? For power-saving functionality or because
of the `quality' factor? What is the criteria that determines the
`quality' of a clock as what's being reported above (I know what
determines the quality of a clock visually from a oscilloscope =])?
I suspect that the quality of the HPET driver is lower simply because no one
had measured it previously and HPET is newer and less "proven".
From memory, HPET was massively slower on some of the AMD test hardware
I was using. There was a thread about it on one of the mailing lists,
but I can't find it right now.
Kris
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