Re: Benchmarking on CentOS 5

[Farkas Levente <lfarkas@bppiac.hu>]

Andrea Arcangeli wrote:
> On Wed, May 28, 2008 at 11:48:21AM -0600, Cam Macdonell wrote:
>> Hi,
>>
>> I wanted to some benchmarking on a CentOS 5 host.  However, the warning in 
>> dmesg about preempt notifiers indicates I shouldn't benchmark.  Is there a 
>> workaround (aside from updating the kernel) that handles the issue?
> 
> The problem is that the preempt notifier emulation through hardware
> breakpoints is worse at optimizing lightweight vm exists than the real
> preempt notifiers supported by recent kernels. If you benchmark
> without upgrading the kernel, it has to be clear it is running slower
> than it would on a recent optimized host kernel. If you decide to
> upgrade and compile the host kernel yourself, you need to configure it
> with CONFIG_KVM=m to be sure the preempt notifiers are enabled in the
> host kernel and in turn the printk will go away.

ok. so what is qumranet recommendation?
the just released latest rhel 5.2 kernel is kernel-2.6.18-92.el5 is it 
good enough for kvm host os? or its' better to change some other distro 
eg: fedora 9?
until now we try to use the latest rhel/centos on all of our servers 
while we use fedora (currently 8 but may be upgrade in a few weeks if 9 
become stable) on desktops. but now it seems probably then for a kvm 
host rhel/centos is not enough:-(

-- 
   Levente                               "Si vis pacem para bellum!"