Re: Benchmarking on CentOS 5

[Farkas Levente <lfarkas@bppiac.hu>]

Andrea Arcangeli wrote:
> On Wed, May 28, 2008 at 10:27:08PM +0200, Farkas Levente wrote:
>> ok. so what is qumranet recommendation?
> 
> I'm not aware of a Qumranet reccomandation for this but I can give you
> my opinion.
> 
>> 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:-(
> 
> This is a almost the opposite question of the previous one from Cam
> ;), here you're asking about a production kernel, Cam was asking for a
> benchmarking setup.
> 
> I think any distro enterprise kernel is better for production systems
> than a latest mainline, but that's just me. You'll find others
> preferring to run 2.6.25 in production a few days after it is
> released.
> 
> The slowdown we're talking about here for the preempt notifiers isn't
> going to make a big difference in a production system, more important
> that you're sure your host kernel is rock solid and well tested
> IMHO. But if it was pure benchmarking what you were doing, then using
> latest mainline was better to get the best possible score, that is why
> such printk is there.

i want rock solid, but smp guest and both 32 and 64bit guest centos too. 
5-10% performance lost is not important but 50-200% is important. so my 
real question is that kernel-2.6.18-92.el5 has "enough" features for an 
good working kvm if i recompile kvm and kvm-kmod? ehough here means no 
more than 5-10% performance lost.

-- 
   Levente                               "Si vis pacem para bellum!"