On Wed, Sep 09, 2009 at 04:00:27PM +0530, Mukesh G wrote:> Hi,> I am trying to understand the behavior of CPU containers as I> am unable to explain few things.> - Built the latest kernel 2.6.30.5 and installed on my Intel core2Duo desktop> > - Mounted the cpu subsystem using> > - mount -t cgroup -ocpu cgroup /containers/cpu/> > - Created 3 sub directories under /containers/cpu> > - 512 for cpu.shares=512> > - 1024 for cpu.shares=1024> > - 2048 for cpu.shares=2048> > - Created 3 bash terminals and attached each one to the individual cpu> sub system using the /bin/echo command. This essentially allows any> process created by the shells to be automatically added to the cpu> subsystem to which the shell belongs> > - Ran a compute intensive benchmark “openssl speed aes-256-cbc”> benchmark on all the shells at the same time.> > - Enclosing the numbers from the run…> > - Observed CPU Utilization : 99.8 , 49.9 , 49.9> > Results from the run> > The 'numbers' are in 1000s of bytes per second processed.> > CPU shares allocation> > 16 bytes 64 bytes> 256 bytes 1024 bytes 8192 bytes> > 512 35459.95k 43441.75k> 46660.35k 46707.71k 77040.30k> > 1024 57448.63k 44050.54k> 46558.98k 46633.03k 47252.76k> > 2048 71186.36k 87142.02k> 92513.79k 93769.05k 94795.09k> > 1024 vs 512 1.62 1.01> 0.99 0.99 0.61> > 2048 vs 1024 1.23 1.97> 1.98 2.01 2> > Observations> > - Unless the cpu resources are overcommitted, there is no> value in the allocating shares to the containers.> - 2048 vs 1024 cpu containers, the scale is 2X, except for 16 bytes> - 512 vs 1024 cpu containers, there is no difference at all,> except for 16 bytes> - 512 vs 1024 cpu containers, there is no difference for 8192> bytes as the remaining 2 openssl runs are complete. (word wrapping has broken your table for me. I will try to decipher itand post observations on it later on.) > - For CPU bound, there has to be an over commit on the CPUs> otherwise the share allocation does not matter Bharata has posted some patches recently athttp://lwn.net/Articles/348578/ which allow one to throttle the amountof CPU bandwidth available to a cgroup. Any feedback on that will begreat! > - One cannot dynamically assign cpus to the container, by> default, it runs on the no of cores available. Right. But you can use cpusets to carve out the system if you want to. -- regards,Dhaval_______________________________________________Containers mailing listContainers@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx://lists.linux-foundation.org/mailman/listinfo/containers
