NTP problem for virtual RHEL 4 server on VmWare

[Yong Huang]

> "The 2.4 kernels have HZ set to 100, while 2.6 kernels have HZ set to
> 1000.  This value affects the frequency of clock interrupts that are
> generated, and those are per-CPU (that's why the problem gets worse
> when you go SMP).  This change in frequency is the main reason for the
> clock problems for Linux guests.  That is why your RH 7.3 works OK,
> while RHEL 4 doesn't.  Another drawback of this change in value of HZ
> is that 2.6 kernels will waste more CPU cycles than 2.4 kernels when
> idling.  Much more.  When you have several SMP Linux 2.6 guests, just
> to keep the kernels running will waste a lot of the available CPU time.
> 
> One recommendation from VmWare is to recompile the 2.6 kernel with HZ
> reduced back to 100 (as it was in 2.4 kernels).  I haven't yet
> attempted this, but I heard reports that it works nicely.

That's only an issue for Linux in VMWare. Correct? My 2.6 kernel RH Linux uses 100 clock tick frequency:

$ uname -r
2.6.9-55.ELsmp
$ cat /etc/redhat-release
Red Hat Enterprise Linux AS release 4 (Nahant Update 7)
$ getconf CLK_TCK
100

I also have RH Linux 5.2 (kernel 2.6.18-92.e15) installed inside Microsoft Virtual PC and it doesn't use 1000.

Yong Huang