[Users] Measuring and Adjusting CPU utilization

[Kir Kolyshkin]

CPU limit is in per cent units. I.e. if your server has a single CPU, 
use --cpulimit 10 to limit a VE to 10% of the CPU.

On a two-way SMP box max. value of cpulimit is 200. Say, if you want a 
VE to use no more than one CPUs, use --cpulimit 100.

Pradeep Padala wrote:

> Thanks for the explanation, but I DID use the --cpulimit parameter.
>
> I set the limit to 1000 units, I run a while(1) loop, and I see a 100% 
> loadavg on the host node. Shouldn't it be somewhere around 10% ?
>
> Pradeep
>
> On 6/6/06, *Kir Kolyshkin* <kir at openvz.org <mailto:kir at openvz.org>> 
> wrote:
>
>     Looks like you misunderstand the concept of cpuunits. cpuunits is
>     not a
>     hard limit, but just a suggestion, and a CPU time is shared
>     proportionally to the values given. So, if you will have 9 VEs and the
>     host system with cpuunits set to 1000 for all of them, and run the
>     loop
>     in all of them, each VE will use 10% of the CPU time.
>
>     In case you will stop the loop running in 5 VEs so there will be 4
>     such
>     VEs (plus the host system) left, each of them will use 20% of the CPU.
>     So, all the CPU time is distributed between VEs which will need it,
>     according with their proportional cpuunits.
>
>     More to say, the concept of "total CPU units" is purely fiction,
>     and is
>     here just for the convenience. People do want to set CPU units is
>     terms
>     of processor's megaherts, and this is what cpuunits does. But in
>     fact it
>     is not a megaherts but just a relative weights. I.e. all the cpuunits
>     values are relative to each other, it doesn't matter what the actual
>     numbers are -- what matters is a number given to a VE in relation
>     to the
>     sum of all cpuweights (which is expressed as "total CPU units"
>     just for
>     the convenience).
>
>     So, cpuunits, if you do not oversell them, are a CPU guarantee, not a
>     limit. If you want CPU limit -- use cpulimit parameter.
>
>     Pradeep Padala wrote:
>
>     > Hi,
>     >
>     > I am trying to measure the CPU utlilization of the VZ
>     containers, and
>     > change the cpu share dynamically. I have poured over most of the
>     > documentation, and looked at the code as well, and it seems like
>     > there's no utility that can directly show the current CPU
>     utilization
>     > of a container (some thing like 30% of CPU). A search on the
>     user list
>     > got me a message, where someone suggested using loadavg.
>     However, It
>     > seems like the loadavg is not showing the proper utilization (or
>     > showing the total CPU utilization). This is what I am doing.
>     >
>     > I setup a container with 1000 units limit (total CPU units:
>     ~10000). I
>     > wrote a small do {; }while(1); loop and ran it in the container,
>     now I
>     > do cat /proc/loadavg in both the container and on the host node.
>     > Since, the container is only using 1000 units, I should see
>     something
>     > like 100% loadavg in the container, and 10% loadavg in the hostnode.
>     > But, I see 100% at both places. Am I doing something wrong? How do I
>     > get the current cpu utilization of a container?
>     >
>     > Thanks,
>     > --
>     > Pradeep Padala
>     > http://ppadala.blogspot.com
>     >
>     >------------------------------------------------------------------------
>     >
>     >_______________________________________________
>     >Users mailing list
>     >Users at openvz.org <mailto:Users at openvz.org>
>     >https://openvz.org/mailman/listinfo/users
>     <https://openvz.org/mailman/listinfo/users>
>     >
>     >
>
>     _______________________________________________
>     Users mailing list
>     Users at openvz.org <mailto:Users at openvz.org>
>     https://openvz.org/mailman/listinfo/users
>     <https://openvz.org/mailman/listinfo/users>
>
>
>
>
> -- 
> Pradeep Padala
> http://ppadala.blogspot.com
>
>------------------------------------------------------------------------
>
>_______________________________________________
>Users mailing list
>Users at openvz.org
>https://openvz.org/mailman/listinfo/users
>  
>