[Fedora-xen] network io load

[Pasi Kärkkäinen]

On Tue, Jul 24, 2007 at 02:05:28PM +0200, Tadeas Mengler wrote:
> Thanks for the reply at first.
> 
> You can see it in htop utility. The load comes from kernelspace. 
> The symptoms are simillar to those: 
> http://lists.xensource.com/archives/html/xen-users/2005-06/msg00625.html
> 

What's the process causing the load / cpu-usage? 

> The speed of for example of coping data across network is very slow
> even on gigabit network (about 3 mbit/s), while domU is extremly slow
> and unresponsive (all of the tasks).
>

Is the network performance slow to begin with, or after some time? If after
some time, what causes it to get slow? 

Is network slow from dom0 to the network?

Is network slow between dom0 and domU ?

What NIC do you have? 

What software are you using to test the network performance? 

Have you tried iperf? both tcp and udp-mode? Do you see packet loss with udp? 

Do you have any errors in logs/dmesg? both dom0 and domU? how about in "xm
log" or "xm dmesg" ?

Do you have any custom settings or xen scheduling parameters (domain
weights) set? 

Are you using (the default) bridged networking setup with xen? Or a custom
one?
 
> The hw varies, mostly supermicro servers, various cpus (different
> intels and amds), various ram , mostly sw raid. The disks are sas, sata.
> 
> The distribution is centos5 with recent updates and current kernel from
> the distribution.
> 

Ok, it should be fine then. I don't see such problems with my hardware and
the same hypervisor/kernels. 

-- Pasi

> 
> Dne Tue, 24 Jul 2007 14:19:55 +0300
> Pasi Kärkkäinen <pasik at iki.fi> napsal(a):
> 
> > On Mon, Jul 23, 2007 at 02:58:42PM +0200, Tadeas Mengler wrote:
> > > Hello
> > > 
> > > I have Xen related issues. I try to describe it as best as I can. 
> > > While transmitting large amounts of data from domU the IO load
> > > increases greatly, thus making the domU unusable. The load is
> > > significant even on dom0. The performance of cpus and hard drives is
> > > not an issue. We have this problem on all servers with diferent hw
> > > configurations. Please do you know the reason of this behaviour, do
> > > you have any experience whith such problems?
> > > 
> > 
> > I'm going to ask you almost the same questions as on centos-list..
> > 
> > Nope, no such experience with many xen hosts.
> > 
> > How do you measure this "IO load" ? What effects does it have?
> > 
> > What kind of hardware do you have (cpu/mem/nic/disk or raid
> > controller/disks)?
> > 
> > Are you running centos5? latest updates installed? or fedora? what
> > fedora version? what kernels? 
> > 
> > Can you post any performance data? How does this "io load" make domU
> > unusable? 
> > 
> > I'm sorry byt your problem description lacks a lot of important
> > information..
> > 
> > -- Pasi
> > 
> 
> 
> -- 
> S pozdravem 
> 
> Tadeas Mengler
> Senior Linux System Administrator
> 
> tadeas.mengler at miton.cz
> 483 367 866, 608 264 866
>   
> MITON CZ, s.r.o. | www.miton.cz
> Jiraskova 9, 466 01  Jablonec nad Nisou
> Tel.: 483 367 800, fax: 483 710 884
>    
> www.stahuj.cz | www.stable.cz | www.otoman.cz | www.vareni.cz 

-- 
       
                                   ^
                                .     .
                                 Linux
                              /    -    \
                             Choice.of.the
                           .Next.Generation.