[Xen-devel] Clocksources and other mysteries

[Carsten Schiers <carsten@xxxxxxxxxx>]

First of all: we are still speaking about am AMD 4050e on MSI M56S-S3 board and
Xen 3.2-1 as well as 2.6.18-xen-3.1-2-amd64 kernel.

I set cpufreq=dom9-kernel and cpuidle. When I use cpufreq-set or if the govenor
is set to cpufreq_ondemand, every frequency change is generating log messages 
that time went backwards. I already understood that this is related to state
changes (both p-state and c-state), nevertheless, I don't understand whether
this messages are indicating a problem. Messages appear in both: dom0 and domus.

My system has a 25 MHz HPET, as xm demsg reports. But in Dom0, jiffies is the
only available (and used) clocksource. In 64 bit domus, it's also only jiffies,
in 32 Bit domus, there is also tsc and pit available, but always jiffies used.

First mystery: when jiffies is used as clocksource, why is the system checking
and complaining about deltas in TSC? Can I thus ignore them?

Second mystery: when Xen reports:(XEN) Platform timer is 25.000MHz HPET, why
isn't Xen using it? Shouldn't it? Wouldn't be the HPET the best choice for my
non-TSC-invariant CPU?

Sorry, if this is not the right place to get better knowledge of Xen 
internals...

Best Regards,
Carsten.

____________________________________________________________________
Carsten Schiers, Henseweg 23h, 22359 Hamburg, Tel. (040) 6044 9717, 
carsten@xxxxxxxxxx

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel