Timekeeping hosed by factor 3, high lapic[01] interrupt rates
Jens Schweikhardt
schweikh at schweikhardt.net
Fri Jun 24 16:50:25 GMT 2005
On Thu, Jun 23, 2005 at 05:14:39PM -0400, John Baldwin wrote:
...
# Ok. What timecounter does your UP kernel use, and does your UP kernel break
# if you change the timecounter to i8254?
The UP uses the TSC:
$ sysctl -a|grep timec
kern.timecounter.stepwarnings: 0
kern.timecounter.nbinuptime: 136311
kern.timecounter.nnanouptime: 0
kern.timecounter.nmicrouptime: 664
kern.timecounter.nbintime: 1273
kern.timecounter.nnanotime: 36
kern.timecounter.nmicrotime: 1237
kern.timecounter.ngetbinuptime: 405
kern.timecounter.ngetnanouptime: 29
kern.timecounter.ngetmicrouptime: 2534
kern.timecounter.ngetbintime: 0
kern.timecounter.ngetnanotime: 0
kern.timecounter.ngetmicrotime: 5
kern.timecounter.nsetclock: 2
kern.timecounter.hardware: TSC
kern.timecounter.choice: TSC(800) i8254(0) dummy(-1000000)
kern.timecounter.tick: 1
kern.timecounter.smp_tsc: 0
When I do
$ sysctl kern.timecounter.hardware=i8254
on the UP the time dilation by factor 3 starts and the lapic rate
increases. So yes, that breaks the UP kernel.
Regards,
Jens
--
Jens Schweikhardt http://www.schweikhardt.net/
SIGSIG -- signature too long (core dumped)
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