On 08/11/2011 06:45 PM, Daniel Lezcano wrote: > On 08/11/2011 11:30 PM, Glauber Costa wrote: >> On 08/11/2011 05:55 PM, Daniel Lezcano wrote: >>> Hi all, >>> >>> the cgroup cpuset and memory reduce access to a part of the resources on >>> the system. Some applications use the /proc/cpuinfo and /proc/meminfo to >>> allocate the resources. For instance, HPC jobs look at /proc/cpuinfo to >>> fork the number of cpu found in this file either look at /proc/meminfo >>> to allocate a big chunk of memory. Each process set the affinity on each >>> cpu, which in case a subset of cpus is used, some affinity will fail. >>> >>> In the case of the container, the cgroup is used to reduce the memory or >>> to assign a cpu to the container. Unfortunately, as this partitioning is >>> not reflected in /proc, the different system tools (ps, top, free, ...) >>> show a wrong information. >>> >>> I was wondering if that would make sense to create for the different >>> cgroup subsystem, when it is relevant, a proc formatted file we can bind >>> mount /proc. >>> >>> For example: /cgroup/memory.proc and /cgroup/cpuset.proc >> >> Not only that. user/sys/nice,etc statistics also are expected to be >> different than the main system one, among other things. >> >> One way I was thinking of doing it, was to always show per-cgroup >> data in /proc files when relevant, using the cgroup of the current >> process as a base. > > That was proposed initially but refused. I tried to do that from > userspace with a fuse filesystem and by translating the cgroup > information into proc information. I was proud of the result but I > noticed fuse is not really friendly with us for the containers: adds a > lot of processes, does not support some file operations and adds an > important overhead, so I gave up because it leads to a deadend. > > http://lxc.sourceforge.net/download/procfs/ Thanks for the pointer. I wasn't aware of such proposal. >> >> bind mounting proc files from their cgroup is a nice alternative, >> though. But it leaves the possibility of any user of it not setting it >> up. > > AFAIK, an user can set up an cgroup, so I guess it is up to the cgroup > creator to handle that. > >> Although it is certainly more flexible, it makes me wonder if a >> constrained process should ever know about resources it can't access... >> >> If bind mounts are used, I'd suggest we represent them as directories, >> like cpuset.proc/cpuinfo. (It is not clear for me what exactly you meant >> in your proposal, sorry if it was just that). > > Well this can not be organized in directory because a directory is a > cgroup :) Sure it can (with some effort). Doesn't mean it should, though, so moving on: > The naming was an example, that would make more sense to name them > cpuset.cpuinfo and memory.meminfo. I might very well be overdesigning, but I guess that once the first files appear, others will follow. So what I'd like to see, is an easy way for future userspace to find out that it should/could bind mount this at proc, regardless of what it is How about cpuset.proc.cpuinfo , memory.proc.meminfo, and so on? Other than this tiny nitpick, specially considering the fact that the alternate proposal I referred to was already rejected, I have to say I really like the overall idea. _______________________________________________ Containers mailing list Containers@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/containers
