On Sat, Jul 24, 2010 at 9:18 AM, Rui Paulo <rpa...@lavabit.com> wrote: > > On 24 Jul 2010, at 14:53, Alexander Motin wrote: > >> Hi. >> >> I've make small observations of Intel TurboBoost technology under >> FreeBSD. This technology allows Intel Core i5/i7 CPUs to rise frequency >> of some cores if other cores are idle and power/thermal conditions >> permit. CPU core counted as idle, if it has been put into C3 or deeper >> power state (may reflect ACPI C2/C3 states). So to reach maximal >> effectiveness, some tuning may be needed. >> >> Here is my test case: FreeBSD 9-CURRENT on Core i5 650 CPU, 3.2GHz + 1/2 >> TurboBoost steps (+133/+266MHz) with boxed cooler at the open air. I was >> measuring building time of the net/mpd5 from sources, using only one CPU >> core (cpuset -l 0 time make). >> >> Untuned system (hz=1000): 14.15 sec >> Enabled ACPI C2 (hz=1000+C2): 13.85 sec >> Enabled ACPI C3 (hz=1000+C3): 13.91 sec >> Reduced HZ (hz=100): 14.16 sec >> Enabled ACPI C2 (hz=100+C2): 13.85 sec >> Enabled ACPI C3 (hz=100+C3): 13.86 sec >> Timers tuned* (hz=100): 14.10 sec >> Enabled ACPI C2 (hz=100+C2): 13.71 sec >> Enabled ACPI C3 (hz=100+C3): 13.73 sec >> >> All numbers tested few times and are repeatable up to +/-0.01sec. >> >> *) Timers were tuned to reduce interrupt rates and respectively increase >> idle cores sleep time. These lines were added to loader.conf: >> sysctl kern.eventtimer.timer1=i8254 >> sysctl kern.eventtimer.timer2=NONE >> kern.eventtimer.singlemul=1 >> kern.hz="100" >> >> PS: In this case benefit is small, but it is the least that can be >> achieved, depending on CPU model. Some models allow frequency to be >> risen by up to 6 steps (+798MHz). > > The numbers that you are showing doesn't show much difference. Have you tried > buildworld?
Agreed. The numbers are small enough that there could be a large degree of variation just based on environmental factors alone; there are other things that go into that as well, such as disk I/O, etc, that probably shouldn't be factored into a CPU performance test. Thanks, -Garrett _______________________________________________ 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"
