Re: ACPI-fast default timecounter, but HPET 83% faster
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 ___ freebsd-hackers@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-hackers To unsubscribe, send any mail to freebsd-hackers-unsubscr...@freebsd.org
Re: ACPI-fast default timecounter, but HPET 83% faster
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. -- John Baldwin ___ freebsd-hackers@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-hackers To unsubscribe, send any mail to freebsd-hackers-unsubscr...@freebsd.org
Re: ACPI-fast default timecounter, but HPET 83% faster
On Thu, 30 Apr 2009 08:46:41 -0400 John Baldwin j...@freebsd.org wrote: On Sunday 26 April 2009 10:27:42 pm Garrett Cooper wrote: 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. http://www.freebsd.org/cgi/cvsweb.cgi/src/sys/dev/acpica/acpi_hpet.c shows some of the history behind the decision. Apparently it used to be slower but it was hoped it would get faster as systems supported it better. I guess that's happening now. -- Bruce Cran ___ freebsd-hackers@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-hackers To unsubscribe, send any mail to freebsd-hackers-unsubscr...@freebsd.org
Re: ACPI-fast default timecounter, but HPET 83% faster
On Mon, Apr 27, 2009 at 01:50:31AM +0200, Pieter de Goeje wrote: While fiddling with the sysctl kern.timecounter.hardware, I found out that on my system HPET is significantly faster than ACPI-fast. I did some extensive testing on a variety of AMD and Intel boards and never found a system where HPET is slower than ACPI-fast. In addition, HPET provides a higher resolution. Joerg ___ freebsd-hackers@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-hackers To unsubscribe, send any mail to freebsd-hackers-unsubscr...@freebsd.org
Re: ACPI-fast default timecounter, but HPET 83% faster
On Sun, Apr 26, 2009 at 4:50 PM, Pieter de Goeje pie...@degoeje.nl wrote:
Dear hackers,
While fiddling with the sysctl kern.timecounter.hardware, I found out that on
my system HPET is significantly faster than ACPI-fast. Using the program
below I measured the number of clock_gettime() calls the system can execute
per second. I ran the program 10 times for each configuration and here are
the results:
x ACPI-fast
+ HPET
+-+
|x +|
|x +|
|x ++|
|x ++|
|x ++|
|x ++|
|A |A|
+-+
N Min Max Median Avg Stddev
x 10 822032 823752 823551 823397.8 509.43254
+ 10 1498348 1506862 1502830 1503267.4 2842.9779
Difference at 95.0% confidence
679870 +/- 1918.94
82.5688% +/- 0.233052%
(Student's t, pooled s = 2042.31)
System details: Intel(R) Core(TM)2 Duo CPU E6750 @ 2.66GHz (3200.02-MHz
686-class CPU), Gigabyte P35-DS3R motherboard running i386 -CURRENT updated
today.
Unfortunately I only have one system with a HPET timecounter, so I cannot
verify these results on another system. If similar results are obtained on
other machines, I think the HPET timecounter quality needs to be increased
beyond that of ACPI-fast.
Regards,
Pieter de Goeje
- 8 - clock_gettime.c - 8 --
#include sys/time.h
#include stdio.h
#include time.h
#define COUNT 100
int main() {
struct timespec ts_start, ts_stop, ts_read;
double time;
int i;
clock_gettime(CLOCK_MONOTONIC, ts_start);
for(i = 0; i COUNT; i++) {
clock_gettime(CLOCK_MONOTONIC, ts_read);
}
clock_gettime(CLOCK_MONOTONIC, ts_stop);
time = (ts_stop.tv_sec - ts_start.tv_sec) + (ts_stop.tv_nsec -
ts_start.tv_nsec) * 1E-9;
printf(%.0f\n, COUNT / time);
}
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 =])?
Thanks,
-Garrett
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