On 06/23/2011 05:51 PM, Balbir Singh wrote: >> Once I have a cgroup struct from cgroup_get_cgroup(), it would be helpful to >> know what controllers it contains. I can get a cgroup_controller struct >> with cgroup_get_controller(), but I need to know the controller name is to >> get that. >> >> Is there a method to return the list of controller names (or controller >> structs) that are in a cgroup? > > I see what you mean, this is the tricky bit and probably an area where > we could improve. We assume the programmer knows what controller is > being dealt with (since the control file names are controller > specific). For example, lets say we want CPU control, then one could > use > > cgroup_get_controller(cgroup, "cpu") to return the controller and then > use the controller further to read values > > If we wanted to set any value, we know the file to set (say > cpu.shares), then we do > > cgroup_add_controller(cgroup, "cpu") and set values in it > > I hope that helps, >
Yeah, it helps me to understand what is expected of the end developer, versus what will be handled in the libcg api. I'm just trying to get my head wrapped around how you all envision the api being used. > FYI: We need to work on a layer 2 API that abstracts all these details > and creates more meaningful names like set_cpu_shares(), > get_cpu_shares(), etc. > > If you don't mind, can I ask how you are using libcgroup, what is the use > case? > We're using cgroups in our render environment to pin batch jobs and their child processes to individual cpu's to avoid processes hopping around to different cores and flushing their caches. Basically each batch job gets its own cgroup with the cpuset controller and we allocate a single cpu to that cgroup. We're also using them to run batch jobs on our interactive workstations without impacting the end user. We're carving off a few cores and a few GB's of RAM from each workstation to run batch jobs on throughout the day. Basically the batch scheduler is dynamically creating and destroying cgroups pretty regularly. I wrote code to do all of that and then realized that libcgroup exists, so now I'm going back through and refactoring to use the api as much as possible. What I found when writing the initial code was that error checking was a giant pain in the neck, especially when removing a cgroup. I'm hoping that the api will abstract most of that away for me. I'm also hoping that I'll be able to reduce some of the hard-coded assumptions I originally made (like we're mounting at /cgroup for example) Thanks for the help so far. -kevin ------------------------------------------------------------------------------ All the data continuously generated in your IT infrastructure contains a definitive record of customers, application performance, security threats, fraudulent activity and more. Splunk takes this data and makes sense of it. Business sense. IT sense. Common sense.. http://p.sf.net/sfu/splunk-d2d-c1 _______________________________________________ Libcg-devel mailing list Libcg-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/libcg-devel
