Hello, Xen Users~!!
I installed xenserver-3.2.0 on my dell
system. When I created a RHEL-4.4 guest OS(2.6.9 kernel) on it,
xen patch changed the timer frequency HZ to
be 100 instead of 1000. And I found the dom0 kernel
also uses a 100HZ instead of 1000HZ.
The general kernel or xen kernel both use USER_HZ
as 100HZ, so I guess, for the applications running mainly in
the user address space, the performance will
be simillar. However, some applications running mainly
in the kernel address space, the
performance will be a lot affected by the differences in HZ between general kernel
and
xen kernel.
My questions are
01.
Why do the xen patches for the
dom0 and domU force to use 100HZ instead of 1000HZ for the timer frequency?
02.
I experienced more significant performance
overhead in 2D graphic operations when I used 100HZ frequency instead of
1000HZ than any other applications such as heavy network IO or disk IO workload.
Could someone have an idea on that?
Thank you!
