Re: Benchmarking on CentOS 5

[Farkas Levente <lfarkas@bppiac.hu>]

this is out production server at the development department (10-15) 
people using it so actually if i tell them that i'll stop the host and 
all guests for max an hour it's acceptable, but more not really. it's 
run it type programs. from my experience in the last 6-12 months is that 
kvm is not production ready. as you can read from this list there are 
far too many change day-by-day which are very core. and this comes from 
the current state of kvm. which indicate that rh can't include in there 
stable server distro such a kvm version which is feature rich and 
stable. i hope rhel 6 will be based on at least kernel-2.6.25 or later. 
and in that case it'll production ready, but even then may be at rhel 
6.1 (since imho rhel 6.0 will be based on a kernel which is released 
nowadays).
imho the biggest problem with the current development of kvm that there 
is not a stable releases which is somewhat related to the current 
release number. eg kvm-0.5.x kvm-0.6.x would be better. but currently 
kvm development is so fast that keep 2-3 parallel branch where there is 
a development and stable release seems to too much work.
so to answer to your question i don't know:-(
i'd like to see a kvm version which is working on rhel/centos 5 host on 
intel and amd, with smp and stable (ie. boot, reboot, save state, a run 
without crash) and the performance is similar (ie 80-90%) to the 
development version. unfortunately it seems currently there is no such 
version:-( may be around 62 one of the version is the best choice.
next week i'll spend a half day to try to find a stable version...

On Fri, May 30, 2008 at 3:38 PM, David S. Ahern <daahern@cisco.com 
<mailto:daahern@cisco.com>> wrote:

    Do you run in a production type environment or lab environment? Do the
    guests run standard IT type programs -- web server, database, etc?

    I ask because something I am working on here might force me to drop back
    to RHEL5, but I still want to use kvm for the virtualization layer. I'm
    trying to get an idea of what to expect. It sounds like it has worked ok
    for you overall, you just have to be picky about specific kvm releases
    you use.

    thanks for the information,

    david


    Farkas Levente wrote:
     > yes as i wrote i always recompile create new rpms for kvm and
    kvm-kmod
     > on centos. the host hasn't any problem (with the last few dozens of
     > kvm), but the guest's are more problematic. we need both 32 and
    64 bit
     > smp guests and it cause a lots of problem. first is the time source,
     > second (as i wrote earlier guest see only 3 of 4 vcpu) and with
    kvm-69
     > we've got a lots of performance lost compared to kvm-62. and see
    random
     > high load on the guests.
     >
     > On Fri, May 30, 2008 at 5:34 AM, David S. Ahern
    <daahern@cisco.com <mailto:daahern@cisco.com>
     > <mailto:daahern@cisco.com <mailto:daahern@cisco.com>>> wrote:
     >
     >     I take it from your posts you are running newer kvm releases
    (e.g.,
     >     kvm-69) on Centos 5 for the host. How's that working out for
    you? Any
     >     major hiccups -- stability issues or runtime issues?
     >
     >     david
     >
     >
     >     Farkas Levente wrote:
     >     > 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!"




-- 
 Levente                               "Si vis pacem para bellum!"

-- 
  Levente                               "Si vis pacem para bellum!"