On Wed, Aug 15, 2012 at 17:21, Mark Kettenis wrote: >> Date: Wed, 15 Aug 2012 11:02:43 -0400 >> From: Ted Unangst <t...@tedunangst.com> >> >> The acpihpet timer is, in my testing, lots better than the acpitimer. >> Faster to read and more precise. They should not have the same quality >> value. Double acpihpet. > > Since both acpitimer(4) and acpihpet(4) are based on an abstract > specification that AFAIK doesn't say anything about the actual > underlying hardware I'm totally unconvinced unless you can show this > to be true on a wide variety of hardware. > > If we do this, the quality of the amdpcib(4) and tcpcib(4) drivers > should probably be raised to 3000. I intentionally assigned them a > higher number than the acpitimer(4) and acpihpet(4) because for these > drivers the underlying hardware is actually known!
Take a look at dmesglog. There are no acpihpet timers slower than 14mhz. If either of the above are present, they are almost certainly the clock you're talking to via acpihpet. acpitimer on the other hand, ticks at a fixed 3mhz. And reading it does this little latching dance I'm not impressed with. I'd be happy making it 1500, if you think there's some possibility that a system would have a bad acpihpet timer and a good amdpcib timer.
