Re: [Condor-devel] Thoughts on cgroups-enabling Condor

[Alain Roy <roy@xxxxxxxxxxx>]

Hi Brian,

I have one small question about cgroups. From the documentation you pointed at, I see:

> Any single subsystem (such as cpu) can be attached to at most one hierarchy.
> As a consequence, the cpu subsystem can never be attached to two different hierarchies.

Does this mean that if Condor uses (for example) the cpuacct subsystem to do process accounting, it will be hard or impossible for other programs on the same system to also do process accounting? Is there currently any common usage of cgroups that would interfere with Condor using it?

-alain

On Jan 1, 2011, at 6:37 PM, Brian Bockelman wrote:
> Hi all,
> 
> During the break, I was able to think more about cgroups and Condor.  For those unfamiliar with cgroups, I think some of the best comprehensive background documentation is provided by Redhat:
> http://docs.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/6/html/Resource_Management_Guide/index.html
> 
> In short, cgroups are a kernel-level construct which provides the functionality of the condor_procd.  I have two goals:
> 1) Improved accuracy for process accounting for memory and CPU usage.
> 2) Improved accuracy for job killing.
> Both (1) and (2) can be done to be basically 100% accurate - no need to worry about short-lived processes or clever fork'ers escaping the watchful eye of the procd.  This can all be done without dedicated accounts or GID tracking.  After examining the procd and starter code, I think these are also doable, short-term goals.