Messages in this thread |  | | | Date | Tue, 31 Oct 2006 11:31:28 +0300 | | From | Pavel Emelianov <> | | Subject | Re: [ckrm-tech] [RFC] Resource Management - Infrastructure choices |
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Paul Menage wrote: > On 10/30/06, Pavel Emelianov <xemul@openvz.org> wrote: >> > Debated: >> > - syscall vs configfs interface >> >> 1. One of the major configfs ideas is that lifetime of >> the objects is completely driven by userspace. >> Resource controller shouldn't live as long as user >> want. It "may", but not "must"! As you have seen from >> our (beancounters) patches beancounters disapeared >> as soon as the last reference was dropped. > > Why is this an important feature for beancounters? All the other > resource control approaches seem to prefer having userspace handle > removing empty/dead groups/containers.
That's functionality user may want. I agree that some users may want to create some kind of "persistent" beancounters, but this must not be the only way to control them. I like the way TUN devices are done. Each has TUN_PERSIST flag controlling whether or not to destroy device right on closing. I think that we may have something similar - a flag BC_PERSISTENT to keep beancounters with zero refcounter in memory to reuse them.
Objections?
>> 2. Having configfs as the only interface doesn't alow >> people having resource controll facility w/o configfs. >> Resource controller must not depend on any "feature". > > Why is depending on a feature like configfs worse than depending on a > feature of being able to extend the system call interface?
Because configfs is a _feature_, while system calls interface is a mandatory part of a kernel. Since "resource beancounters" is a core thing it shouldn't depend on "optional" kernel stuff. E.g. procfs is the way userspace gets information about running tasks, but disabling procfs doesn't disable such core functionality as fork-ing and execve-ing.
Moreover, I hope you agree that beancounters can't be made as module. If so user will have to built-in configfs, and thus CONFIG_CONFIGFS_FS essentially becomes "bool", not a "tristate".
I have nothing against using configfs as additional, optional interface, but I do object using it as the only window inside BC world.
>> > - Interaction of resource controllers, containers and cpusets >> > - Should we support, for instance, creation of resource >> > groups/containers under a cpuset? >> > - Should we have different groupings for different resources? >> >> This breaks the idea of groups isolation. > > That's fine - some people don't want total isolation. If we're looking > for a solution that fits all the different requirements, then we need > that flexibility. I agree that the default would probably want to be > that the groupings be the same for all resource controllers / > subsystems.
Hm... OK, I don't mind although don't see any reasonable use of it. Thus we add one more point to our "agreement" list http://wiki.openvz.org/Containers/UBC_discussion
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