[CentOS] vmware-time update issues and typematic issues
alex at milivojevic.org
Sat Sep 23 12:26:41 UTC 2006
> right now system times are off 2 mins after all nite ...yest. that would
> have been 10-12hrs. I stopped all ntp or whatever that is...going out to
> one of the time servers...just getting time from the host system.
Some hints from the vmware website for 2.6 kernels say to use
"clock=pit" kernel option in guests, disable NTP in guests (system
clocks in virtual machines are too unstable), and let vmware tools sync
the time with the host OS (you can use NTP to sync the time of the host
OS with some time source, of course).
If you have both 2.4 and 2.6 kernels running in guests, you'll probably
notice that 2.6 kernels are taking 3-4 times more CPU time when the
guest is idling. That's because the default frequency of interrupts
changed from 100Hz to 1kHz (and that is per CPU) in 2.6 kernels.
Placing much more stress on vmware and causing all bunch of problems
with it. It's configurable compile time option (you'd need to recompile
kernel to change it to the old default). I have one (not really brand
new anymore) dual-Xeon machine that runs ESX with 5 2.6 guests and
couple of 2.4 guests. When all the guests are idle, they consume about
half of the CPU time of one processor. I haven't yet attempted
recompiling 2.6 kernel and lowering frequency of interrupts, but it's
probably worth trying.
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